THE NEW ZEALAND OFFICIAL YEAR-BOOK, 1942

By reason of its elongated shape, New Zealand possesses a very lengthy coast-line in proportion to its area. With the exception of the low-lying North Auckland peninsula, the length of the New Zealand land-mass lies along a south-westerly-north-easterly axis, and thus parallel to the direction of its mountain-chains.

By reason of the latter fact the coast-line is, on the whole, not greatly indented; and, as a consequence, New Zealand is not well endowed with natural harbours. In the North Island, Auckland and Wellington are the only two safe natural harbours of which the fullest commercial use can be made. On the east coast of the North Auckland peninsula several deep and sheltered harbours exist, but as the surrounding country is comparatively undeveloped and the area somewhat remote they are of little economic consequence at present. In the South Island the Marlborough Sounds and the West Coast Sounds form perfect land-locked harbours, but owing to their situations and to the rugged nature of the terrain they have—with the exception of Queen Charlotte Sound—little or no commercial utility. Where vital localities have not been endowed with ideal harbours it has been necessary to improve existing facilities by dredging and by breakwater-construction, &c. In this manner efficient ports, capable of accommodating overseas vessels, have been formed in Lyttelton, Otago, and Bluff harbours. On the west coast of both Islands the strong ocean-drifts and high seas cause shoaling at river-mouths and harbour-entrances, while on the east coast of the South Island similar circumstances prevail, due to the large quantities of shingle brought down by the rivers being spread along the coast by ocean currents. The mountainous nature of the country makes the haulage of goods to and from the better-equipped natural harbours both costly and difficult, and the construction and maintenance of further ports at various points along the coasts of both Islands has been necessary, either by dredging river-mouths or by harbour-construction work.

The mountainous nature of New Zealand is one of its most striking physical characteristics. In the North Island the higher mountains occupy approximately one-tenth of the surface; but, with the exception of the four volcanic peaks of Egmont (8,260 ft.), Ruapehu (9,175 ft.), Ngauruhoe (7,515 ft.), and Tongariro (6,458 ft.), they do not exceed an altitude of 6,000 ft. Of these four volcanoes only the first-named can be classed as extinct. Other volcanoes include Mount Tarawera and White Island, each of which has, upon one occasion within historical times, erupted with disastrous consequences. Closely connected with the volcanic system are the multitudinous hot springs and geysers.

The South Island is much more mountainous than the North, but shows fewer manifestations of recent volcanic activity. Along almost the entire length of the Island runs the massive chain known as the Southern Alps, which attains its greatest height in Mount Cook (12,349 ft.), while no fewer than seventeen peaks exceed 10,000 ft.

The position and trend of the mountains in New Zealand exert considerable influence on the economic life of the Dominion. Attention has already been drawn to the relation between the direction of the mountains and the nature of the coast-line, while in the article dealing with climate (post) mention is made of the effect of mountains on climatic conditions.

As may be expected, the higher mountains of the South Island have exerted a greater influence on the economic development of the country than those of the North Island. For many years the Southern Alps were an effective barrier to communication by land between the cast and west coasts, while their climatic effects on the Canterbury plains and Otago plateaux determined the types of cultivation undertaken. Moreover, the existence of much elevated open country led to the development of pastoral holdings on a large scale. While the mountains in the North Island are not as high nor as extensive as those of the South Island, in the early days they effectively isolated various portions of the coastal plains and valleys. Their effect on climatic conditions, however, is considerably less, the rainfall being more evenly distributed. Duo to this more even distribution of the rainfall, and to the existence of considerable areas of lower relief, the foothills of the mountain systems were heavily wooded, and so proved a hindrance to agrarian development.

In the 1931 issue of the Year-Book was given a list, not claimed as exhaustive, of 223 named peaks of 7,500 ft. or more in altitude. Below is a list of the peaks, restricted to the three largest volcanic cones in the North Island and to mountains of a minimum height of 9,000 ft. in the South Island. The list has been compiled from various sources, and does not purport to be free from omissions.

In keeping with the dimensions of her mountain system, New Zealand possesses, in the South Island, a glacial system of some magnitude. Of the glaciers the largest is the Tasman, which, with others of comparable size, rises in the more elevated area surrounding Mount Cook. Flowing down the eastern slope of the range, this glacier has a length of 18 miles and a width of 1¼ miles. In common with other glaciers on the eastern slope, of which the more important are the Murchison (11 miles), the Mueller (8 miles), the Godley (8 miles), and the Hooker (7¼ miles), its rate of flow is slow, while its terminal face is at an altitude of somewhat over 2,000 ft. On the western slope of the range, owing to the greater snow precipitation, the glaciers are more numerous and descend to lower levels, while the steeper slope gives them a faster rate of flow. The two largest of these are the Fox and the Franz Josef, with lengths of 9¾ miles and 8½ miles respectively, and terminal faces at altitudes of 670 ft. and 690 ft.

As will be realized, these glaciers are an important tourist attraction, and as such have definite economic significance. Moreover, those glaciers on the eastern slopes which feed rivers utilized for irrigation and hydro-electric purposes are valuable in that they help to ensure a steady volume of water throughout the year.

Of the numerous New Zealand rivers few are of sufficient length or volume to be navigable. Moreover, owing to the high relief of the country, they are mostly swift-flowing, while, as mentioned previously, nearly all are obstructed at their mouths by bars. For the purpose of internal communication, therefore, they are of little economic utility, and only in two or three isolated instances have they been thus consistently used. With improved roading conditions, however, their traffic has become negligible even in these cases.

As sources of hydro-electric power, New Zealand rivers are of considerable importance, since their rapid rate of flow and dependable volume of ice-free water make them eminently suitable for this purpose. At the present time the Waikato and the Mangahao rivers in the North Island and the Waitaki River in the South are used for major hydro-electric schemes. The characteristics just mentioned are also important for purposes of irrigation, but, owing to the country's reliable rainfall, there are few areas other than in Canterbury and Otago where the rivers are so utilized.

In the 1932 Year-Book appears an account of the rivers of New Zealand by Professor R. Speight, M.Sc., F.G.S., Curator of the Canterbury Museum.

Space in this issue is, however, available only for a list of the more important rivers, with their approximate lengths, the latter being supplied by the Department of Lands and Survey. Figures in parentheses indicating the approximate discharge, in cubic feet per minute, are shown for the largest rivers.

NORTH ISLAND.

SOUTH ISLAND.

The discovery in 1861 that the beds of numerous rivers in the South Island contained extensive deposits of alluvial gold was of considerable importance in the economic development of the country. Not only did it lead to an increase in population and in wealth, but, through the following of the numerous streams to their sources, it also led to the rapid exploration of large tracts of remote country. The exploitation of these deposits has been carried on with varying degrees of success up to the present time by both manual and mechanical means.

A further factor in connection with the rivers is that, owing to the very successful acclimatization of fresh-water fish, notably trout, many of them now provide exceptionally fine fishing.

In considering New Zealand's numerous lakes, a distinction can he made, especially from the scenic viewpoint, between the lakes of the two Islands. Surrounded by extremely rugged country the larger lakes of the South Island are distinguished by the grandeur of their alpine settings, while those of the North Island, situated on a volcanic plateau, are of interest by reason of the neighbouring thermal activity. Due to the excellence of their fishing, the latter possess an added tourist attraction. In both Islands the larger lakes are situated at high altitudes, and their consequent remoteness renders them unsuitable as a means of communication. In their functions as reservoirs the lakes of both Islands are of vital importance for the maintenance of the streams draining them and as a means of flood-prevention. More especially is this the case where hydro-electric schemes are involved, Lakes Waikaremoana and Taupo in the North Island, and Lakes Coleridge, Pukaki, and Tekapo in the South Island, being of particular significance in this respect.

An article on the lakes of New Zealand, also by Professor R. Speight, will be found in the 1932 Year-Book. Some particulars of the more important lakes are given below.

Earthquake and volcanic activity are manifestations of the adjustments constantly occurring in the earth's crust. In the not far distant past, geologically speaking, a more or less continuous belt of mountains was raised up round the border of the great sunken area of the Pacific, and this belt as a whole is characterized by “chronic and acute seismicity.” At times the earthquakes occur within the belt itself, though a large proportion have their epicentres on its submerged frontal slope.

The South Island of New Zealand and the eastern part of the North Island are on the crest of the great mountain ridge or crustal fold which forms a portion of the real border of the Pacific. This ridge maintains a relatively straight course north-north-east for 1,600 miles across the floor of the Pacific, nearly to Samoa The Auckland Peninsula, part of a decidedly weaker fold, meets the main fold nearly at right angles in the Rotorua-Taupo volcanic region. The earthquakes of this seismically sensitive district, though they may be locally severe, are not usually felt far from their points of origin. On the other hand, the tectonic earthquakes that occur along the main earth-fold shake large areas, some of them being recorded on instruments throughout the world. These ore caused by the slipping of earth-blocks against their neighbours along fractures.

Many great fault-zones have been traced for long distances, but a few only have been active since European occupation. The Hawke's Bay earthquake of 1931 raised an area sixty miles long in a north-east direction and in parts ten miles wide. The uplift was greatest along the south-east edge of the area—for miles amounting to 6 ft. or more. Numerous levels on the Heretaunga Plain and along the railway north of Napier show that the uplift decreased north-westward, so that the area was slightly tilted in that direction. The ground east of the uplifted area sank, and parts of the Napier and Wairoa flats are over a foot lower than before the earthquake.

In 1929, movement along a north-trending fault seven miles west of Murchison raised the ground east of the fault by about 15 ft., and caused it to shift north-west by about 9 ft. The uplift gradually decreases eastward and dies out sixteen miles from the fault, facts indicating a slight tilt of the earth-block toward the east. Subsequent levellings showed that the block was sinking somewhat irregularly, a movement, no doubt, which caused some of the innumerable local after-shocks felt in the area over many months after the main shock. Other sensible earth-movements occurred in connection with the Taupo earthquake series of 1922,^* the Amuri earthquake of 1888,^† the Wellington earthquake of 1855,^‡ and probably the Awatere earthquake of 1848.^§ There is also definite evidence of geologically recent differential movement of earth-blocks at several widely separated points in both Islands.

A comparison between the records of destructive earthquakes in New Zealand and those in other seismic countries shows that the seismicity of New Zealand, on the whole, is surprisingly high. However, this is due to the occurrence of a large number of earthquakes of the semi-destructive type (R.-F. 8) with comparatively few major destructive shocks (R.-P. 9, 10).

During the period 1835-1934 sixty-nine destructive earthquakes are known to have occurred in New Zealand, forty-nine of which were of the semi-destructive type (not exceeding intensity R.-F. 8). Of the remainder, fourteen were of intensity 9, and six of intensity 10.^||

The total number of earthquakes of all intensities, and the maximum intensity, reported felt in New Zealand in each of the years 1921 to 1940 were as follows:—

* P. G. MORGAN: N.Z. Geological Survey; Annual Report for the year 1923, p. 10.

† ALEXANDER MCKAY: Reports of Geological Explorations during 1888-89. Wellington, 1890.

‡ New Zealand Government Gazette, Wellington, Vol. 2, No. 14, 17th October, 1855, p. 116. Sir CHARLES LYELL, “The Principals of Geology,” tenth edition, 1868, Vol. 2, p. 82, London: John Marray.

§ New Zealand Government Gazette, Wellington, Vol. 1, No. 27, 13th November, 1848, and Vol. 1, No. 29, 20th November, 1848. H. S. CHAPMAN in Westminster Review, Vol. 51, 1849.

|| L. BASTINGS: “Destructive Earthquakes in New Zealand, 1835-1934,” N.Z. Jour. Sci. & Tech., Vol. 17, No. 1, July, 1935. Dominion Observatory Bulletin 103.

The abnormally large number of earthquakes reported in the year 1922 was due to the swarm of local shocks in the Taupo region in the latter half of that year. Abnormally large numbers of shocks also occurred in 1929-30, due to aftershocks of the Buller earthquake of 17th June, 1929.

New Zealand earthquake statistics over the past hundred years or so show that certain parts of the country are subject to almost continuous seismic activity with occasional destructive shocks, while other parts are more or less free from seismic disturbances. By combining early earthquake records with the more precise data of recent years it is possible to divide the country roughly into four seismic regions.

These regions are classified below, in order of seismicity:—

The following table shows the average frequency of earthquakes in each of the four regions defined above:—

It will be seen from the above table that region I, on the average, has nearly 100 (97.8) shocks per year, with major destructive shocks from time to time.

In region II, there is an average of 23 shocks per year, with about one minor destructive shock per decade. The activity in this region tends to increase gradually towards the east and south, where it merges into region I.

In region III no major destructive shocks and only one semi-destructive shock have been recorded definitely. This occurred in the Mount Cook region. However, early history suggests that heavy shocks occurred in the West Coast Sounds region in the years 1792, 1810, 1826-27.^* It is possible, therefore, that seismic activity on the western side of the Island is slightly higher than indicated in the above table. On the other hand, the eastern side is less seismic than the western.

Region IV has very low seismicity. An average of one shock per year is experienced, and no destructive shocks have been known to occur.

In connection with the above facts, it must be emphasized that the boundaries between the seismic regions are not well defined, since one region generally merges more or less imperceptibly into another. Also, that seismic frequency is not uniform. This leads to the number of shocks being considerably above the average in some years and below it in others. The normal irregularity is increased by the occasional occurrence of earthquake swarms in certain regions. Probably the most notable swarm in New Zealand was that which occurred in the Taupo region in the latter half of 1922. The number of minor local shocks in this swarm was so great that only the stronger ones, or those affecting the adjacent region, were used in determining the average frequency of region I. The inclusion of all shocks would unduly raise the average frequency of this region as a whole.

* R. MCNAB: “Murihiku and the Southern Islands” (1907). R. TAYLOR: “Te Ika a Maui,” London, 1855.

During the period 1848-1940 the number of deaths recorded in New Zealand as due directly or indirectly to earthquakes was 284. Of these, 255 were due to the Hawke's Bay earthquake of 3rd February, 1931. A table giving details of the number of deaths due to earthquakes in New Zealand was published in the 1938 issue of the Year-Book.

Earthquakes in New Zealand are recorded by means of seismographs, and also by a system of non-instrumental reports. The main seismograph stations are located at the Dominion Observatory, Wellington, and the Magnetic Observatory, Christchurch. The Dominion Observatory acts as a central station for ten other subsidiary stations in New Zealand and one at the Chatham Islands. The subsidiary stations are operated by officers of other Government Departments, by engineers of some of the Electric-power Boards, and by private individuals. The non-instrumental reporting-stations are located chiefly at post-offices and lighthouses.

The New Zealand Meteorological Office is situated at Kelburn, Wellington; to this is attached the Apia Observatory, Samoa, while branch offices are located at Auckland and at the R.N.Z.A.F. Stations at Ohakea, Woodbourne, and Wigram.

Regular weather forecasts based on observations at 9 a.m. and 3 p.m. are issued at noon and 5 p.m. respectively. Under the present censorship regulations the transmission by the Broadcasting Services of weather reports and forecasts has been suspended, but district forecasts are still supplied to the press and to certain post-offices. The forecasts cover the twenty-four hours following the time of issue while in many cases a “further outlook” is appended to indicate the general prospects for the day or two following the close of the forecast period.

The New Zealand Gazette includes each month a meteorological section which contains a detailed climatological table for Kelburn, general notes on the weather for the previous month throughout New Zealand, and a table summarizing climatological data from over sixty stations. Fuller tables of a similar nature are published annually by the Meteorological Office. Hitherto rainfall data from a further five hundred stations accompanied the other meteorological information in the New Zealand Gazette, but are now to appear in a separate annual publication. Papers on various aspects of the climate and weather of the Dominion are issued from time to time as “Meteorological Office Notes.”

New Zealand lies wholly within the Temperate Zone, and it is also wholly and at all seasons within the zone of prevailing westerly winds though they are stronger and more persistent farther southward. Owing to the isolation of the country and its narrowness in the direction of the prevailing winds, its climate is predominantly marine in character. Nevertheless, the modifications due to the height and continuity of the main ranges and the general high relief of the country are quite considerable, especially in the South Island. There is, for example, a very great variation in the rainfall from the western to the eastern side of the Southern Alps, and for so narrow a country, features of a continental type are rather strongly developed in the interior of the South Island. By breaking up the prevailing winds and causing the air at different levels to mix, mountains tend, also, to prevent the stratification of the air into layers of different density. Consequently very extensive and persistent cloud-sheets are seldom experienced. New Zealand therefore enjoys a high percentage of sunshine, a factor of great importance in the climate of a country with a high rainfall.

The principal current in the surrounding ocean waters is from south-west to north-east. Off the west coast of the South Island, however, the current divides, one branch turning southwards to Foveaux Strait, while others pass through Cook Strait and round the northern extremity of the Dominion. The rather small range in climate from north to south is probably accounted for by this current.

According to the widely accepted classification of climates developed by W. Köppen, New Zealand has the climatic formula Cfb, denoting a cool-temperate moist climate without marked seasonal variations in temperature or precipitation. Under the same formula are classified southern Victoria and Tasmania and parts of southern Chile in the Southern Hemisphere, much of Europe, Japan and Korea, and a strip of the west coast of North America in the Northern Hemisphere. Generally, however, it is a climate characteristic of the ocean rather than the land areas of the Temperate Zone.

^{Tables 1} to ³ appearing in the following pages relate to varying, but usually lengthy, periods. In ^{Table 4} the duration covered by the respective averages for that table is given.

Of all the climatic elements, probably the one that exerts the greatest influence on our lives is rainfall. It causes us much personal discomfort, but the production of the food by which we live depends directly on the availability of moisture from this source. Maps showing the distribution of mean annual rainfall appeared in issues of the Year-Book prior to 1934.

The controlling influence of topography on rainfall in New Zealand is very conspicuous. Areas exposed to the westerly winds have heavier rains than those protected from them by mountain ranges. Next, the greater the altitude the greater in general is the precipitation. There must be a limit beyond which precipitation begins to decrease again with altitude, but this has not yet been determined in this country. The indications are that precipitation is heaviest between 3,000 ft. and 4,000 ft. The annual total varies from about 13 in. about the Alexandra-Galloway district in Central Otago to well over 200 in. in parts of the Southern Alps and on Mount Egmont.

The distribution of the precipitation throughout the year is little less important than its total amount, the effect of rainfall in winter, for example, being very different from that in summer. There are three principal factors controlling the annual variation of rainfall in New Zealand. The first of these is the proximity to the high-pressure bolt in the subtropics. In this belt the rainfall year is divided into a dry summer and a wet winter season. We will call this distribution type A. As the distance from the high-pressure belt increases, the contrast between summer and winter decreases, so that by the time southern New Zealand is reached the variation due to this factor is small. The next most important factor is the influence of the prevailing westerly winds. These bring rains to the areas exposed to them, while areas which are protected from them by mountain ranges have little rain when the westerlies are blowing. The westerly winds are strongest in spring, the maximum flow being in October. There is a temporary drop in February, followed by a partial recovery in the autumn, but the flow is least in winter. The régime of the westerly winds, therefore, tends to produce a second type of annual variation, type C, in which the rainfall is heaviest in spring, decreases somewhat in the late summer, increases again in the autumn, and decreases to a minimum in winter.

The third factor is the convection which takes place during periods of light winds, clear skies, and intense sunshine, especially when the preceding winds have brought cold air over the land from the south. After conditions of the type mentioned have endured for several days, the convection is likely to be so intense as to produce local showers. These are often heavy, sometimes accompanied by thunder, and occasionally of the nature of local cloud-bursts. Rainfall of this type is most common in the interior of continents. Being caused by solar radiation, it is most frequent when solar radiation is strongest—namely, in summer. According to type B, therefore, we would have a relatively wet summer and a dry winter.

A rainfall régime of type A in a fairly pure form is experienced in the part of the Auckland Province, north, roughly, of Kawhia and Tauranga, and on the eastern side of the main ranges from Cook Strait to East Cape. It is still dominant in the lower country about the Tasman and Golden Bays, and in Marlborough and North Canterbury. Type C is developed strongly in Westland and the south-west Fiord country. It is shown fairly well by Hokitika, but much more distinctly if the data for a number of West Coast stations be combined. It is dominant in the far South, in the mountains of Nelson, and in the portion of the North Island not yet referred to. In this latter area, however, types A and C combine in varying proportions. Most districts show the effect of the westerly winds in a relatively high rainfall in October, but this is least noticeable in the low country east of the main ranges. The areas where type C dominates are those with the heaviest rainfall. Type B is dominant in the interior and southern portions of Canterbury and the central and eastern portions of Otago, and is especially characteristic of the dry areas of the provinces mentioned. The summer rains of this type are of great importance to the farming communities in the interior of Canterbury and Otago. The régime of annual rainfall experienced had an important influence in determining the nature of the primitive vegetation in the various districts.

Next to the amount and the annual variation of precipitation, the frequency with which it falls is its most important characteristic. In ^{Table 2} the average number of days with rain in each month is given for some representative stations. A day with rain is one on which 0.005 in. or more is measured. Generally speaking, there is a fairly close relationship in New Zealand between the amount of rain and the number of rain days, but the latter is not directly proportional to the rainfall. There are considerable areas on the west coast of the South Island, for instance, which have ten or more times as much rain as the driest portions of the interior, but only about double the number of rain days. Marlborough seems to have a small number of wet days compared with its rainfall. To the south of New Zealand there is a rapid increase in cloudiness, showers fall with great frequency, and the number of rain days becomes high. New Zealand is extremely fortunate in that, even where the rainfall is very heavy, intervals between rains are almost everywhere sufficiently frequent and prolonged to ensure adequate drainage, while there is enough sunshine to dry the soil surface. Otherwise, large areas in the west and south would be covered with peat.

Temperature is no less important than rainfall in determining the living conditions of a country and the yield from its soil. But it is much less variable, and in the Southern Hemisphere especially, is largely determined by latitude. Its influence is therefore taken much more for granted. The specification of the temperature of a place is, however, not so simple a matter as might appear. Many different factors are involved in the determination of the precise temperatures experienced in any locality. The sea, for instance, responds very slowly to both daily and yearly changes in the amount of heat received from the sun, while on the land the response is rapid. Consequently, the nearer a station is to the sea the smaller are its daily and yearly fluctuations of temperature. It is to this effect that the principal difference between a continental and a marine climate is due. Although New Zealand is narrow, the high ranges shield the country to the east of them to a considerable extent, so that there is a nearer approach to continental conditions than would otherwise be expected, particularly in the interior of Canterbury and Otago. Again, on plain country the air tends to stagnate, especially at night. At night-time the surface layer cools rapidly through radiation from the ground, while during the day it becomes heated by the sun. There is less stagnation in the warm layer of the daytime than in the cold layer of the night. Consequently, stations on level plains or plateaux tend to be subject to frost and to have a relatively low mean temperature. The effect is accentuated near the slopes of hills because the cold air flows away down the slopes to lower levels. The hills, therefore, gain freedom from frost at the expense of the plains, In windy situations, also, the susceptibility to frost is lowered owing to the prevention of stagnation. Apart from the effects due to air-drainage and windiness, the temperature decreases with altitude. In temperate latitudes the fall is about 9° F. per kilometre. It is unsound, therefore, to compare, for example, temperatures recorded at Thorndon, Wellington, which was only 12 ft. above sea-level, with those at the present meteorological station at Kelburn, which is at an altitude of 415 ft., without making allowance for this difference in altitude. Such a procedure would lead to the erroneous conclusion that the climate had become colder. If charts of mean temperature are to be prepared it is clear that they will be very complicated, especially in a mountainous country like New Zealand, owing to this effect of altitude. It is usual, therefore, to simplify matters by applying a correction at the rate of 9° F. per kilometre or approximately 2.7° F. per 1,000 ft. This has been done in ^{Table 3}. The Rotorua values, for example, have been increased by 2.5° F., the station being 925 ft. above sea-level. If the actual temperature is required, it can be found by reversing this process.

In New Zealand publications it has been the general practice to derive monthly mean temperatures from the means of the daily maximum and minimum. But, even on the average, the mean of the maximum and minimum differs slightly from the true mean for the day. The correction to the mean for the day has been determined from the records of thermographs at Wellington and more approximately at several other places.

In ^{Table 3}, therefore, the temperatures are reduced to sea-level and mean of day, and are expressed in Fahrenheit degrees.

The stations given in the above table were chosen with a view to illustrating the effect of changing latitude, the difference between east and west coasts, especially in the South Island, and the contrast between coastal and inland conditions. Waipoua is in the Auckland Peninsula, north of Dargaville, and Ophir in Central Otago.

Tables setting out information about maximum and minimum temperatures at certain stations are to be found in the 1940 and earlier editions of the Year-Book.

In ^{Table 4} is listed for each month and the year the average number of hours of sunshine at a selection of places from which sufficiently long records are available. The greatest amounts are recorded at places protected from the prevailing winds by high mountain ranges. The excellence of New Zealand's climate, particularly for the growth of pasture, is undoubtedly due to the abundance of sunshine combined with a high rainfall and an absence of extreme temperatures.

Fog.—Fog does not play an important part in New Zealand weather. Most of the fogs recorded are shallow radiation fogs occurring only in the early morning. During the approach of cyclonic depressions, however, widespread and persistent fog is a frequent occurrence. Occasionally, parts of the coast are affected by fog in calm weather. The landlocked harbours and estuaries of North Auckland appear to be unusually susceptible.

Snow.—Snow is rare at sea-level, especially in the North Island. In the interior and at high altitudes it occurs more frequently. On the summits of the ranges in the whole length of the South Island and on the highest peaks in the North Island snow falls, on the average, on over thirty days per annum. In the interior of the South Island there is a considerable area of settled country which is subject to half that number. Towards the coast, however, the number falls off rapidly. Data regarding snow lying are scanty. In the North Island any snow falling on the low levels almost invariably melts as it falls, but on the high plateaux it may lie, especially in the hollows, for from one to three weeks during the year. In the South Island it practically never lies at low levels on the north or west coasts, but on the east coast does so on a few days in some years. At altitudes between 500 ft. and 1,000 ft. in the interior of the South Island the average number of days appears to be between seven and fourteen. Railway traffic is seldom interfered with by snow, even to a minor extent.

Hail.—Hail is experienced more frequently as the latitude increases, and more often on the west coast than on the east, the rise in frequency in the extreme south-west and about Foveaux Strait being very marked. It occurs more often in spring than at other times of the year. The majority of the hailstorms recorded, however, are harmless, the stones being quite small, though occasionally severe hailstorms are experienced in New Zealand, with stones reaching a diameter of from ½ in. upwards. The latter are usually associated with thunderstorms, and are probably a little less numerous on the east coast than the west, or in the North Island than in the South.

Thunder.—Thunderstorms are more numerous in the North than in the South and on the west than on the east side of the main ranges. They are very rare in eastern districts in winter.

Strong Winds.—The average numbers of days per year when the wind has been reported as reaching gale force (force 8 and over on the Beaufort Scale) are: Auckland, 14; New Plymouth, 15; Wellington, 21; Hokitika, 2; Christchurch, 7; Dunedin, 10; and Invercargill, 20. Anemometer records over the past few years show that the average number of days on which there is at least one gust of wind exceeding 40 miles an hour is 34 at Hobsonville, Auckland; 137 at Kelburn, Wellington; and 30 at Wigram, Christchurch. The Wellington figures show the effect of the frequent concentration of the winds through Cook Strait.

A Brief Review.—The summer of 1939-40 continued wet and the following autumn months were cool. The winter was unusually pleasant, with very little severe weather, and the ranges received much less snow than usual. Spring was well advanced and, in spite of a windy October and a cool November, most crops had an admirable season. Bumper hay harvests were brought in early, and before the year closed dairy production had reached a high level, while stock and crops continued in excellent condition.

For the year as a whole windy weather was rather less prevalent than usual, although orchards suffered from occasional gales. Mean temperatures, except in the south-eastern portion of the South Island, were slightly below normal. Rainfall tended to be deficient over most of the Auckland, Nelson, and Marlborough Provinces, as well as over an area including the Manawatu and Wanganui. Appreciable excesses were restricted to several small areas, chief of which were those located near Portland Island, Otira, and Southland.

Seasonal Features.—The chief characteristics of the seasons are now described in more detail.

At the beginning of the year conditions were warm and humid. Stormy weather between the 12th and 15th January gave some heavy downpours, especially in the far north. Although in February the Auckland Peninsula and districts between Banks Peninsula and East Cape were dry, elsewhere the month was wet. Persistent westerly winds carried frequent rains to western and far southern districts, which experienced a record wet February. In the case of Southland this was the wettest of any month ever experienced. The registration of 72.74 in. at Homer Tunnel gauge was the greatest monthly total yet to be measured in New Zealand. On the 23rd and 24th February a cyclonic disturbance gave heavy falls in King-country and Taranaki, where severe floods and slips damaged and blocked roads and railways. In Central Otago and Westland it was a record February for coldness. March, however, was a fine month with sunny days and frosty nights. Rainfall was well below normal, but this was no drawback, except in Mid-Canterbury.

In April unseasonable conditions returned, the month being, on the whole, as cold as any previous April. Southerly winds accompanied by showers were frequent throughout, but the totals were not excessive, except between Canterbury and East Cape. May likewise was cool with frequent rain, totals being well over normal in Otago and Canterbury, chiefly as a result of the continuous southerly rains between the 4th and 8th, which produced extensive flooding and traffic dislocation, particularly in the Taieri Valley.

The winter season was remarkably good with only light rainfalls.

Spring commenced with a mild September, during which frequent scattered rains and warm soil temperatures accelerated an early season characterized by prolific blooms. Canterbury had substantial rainfall, and excesses occurred thence northward to Hawke's Bay, while deficiencies were most marked over the Auckland Peninsula. October was rather cool and windy, gales being widespread on the 27tb and 28th. It was dry from Canterbury southward, but heavy precipitation occurred in Westland on the 18th and in the Southern Lakes district on the 28th, followed by serious floods.

During November sufficient showers fell in the South Island cereal-growing districts to bring relief at a critical time. There was considerable thunderstorm activity during this period. December was warm, sunny, and dry, except for areas in Central Hawke's Bay and between Taupo and Tauranga, which were most affected by torrential rain on the 14th.

SUMMARY OF METEOROLOGICAL OBSERVATIONS FOR 1940.

(The observations were taken at 09.00 hrs., N.Z. standard time.)