GENERAL

CLIMATE

[The section on climate is contributed by the Meteorological Department. Government of India, Poona.]

Seasons.

The climate of this district is on the whole dry except during the south-west monsoon season. The year may be divided into four seasons. The cold season from December to February is followed by the hot season from March to May. The south-west monsoon season which follows thereafter lasts till September. October and November constitute the post-monsoon season.

Rainfall.

Records of rainfall, in the district are available for 9 raingauge stations for periods ranging from 58 to 93 years. Tables 1 and 2 give the details of the rainfall at these stations and for the district as a whole. The average annual rainfall in the district is 674.0 mm. (26.53"). The rainfall is heavier in the hilly regions of the western ghats and the Satpuda ranges. Navapur near the western border has an annual rainfall of 1097.1 mm (43.19"). The rainfall during the south-west monsoon constitutes about 88 per cent of the annual rainfall, July being the rainiest month. Some rainfall is received mostly as thunder-showers in the post-monsoon season. There are variations in the rainfall from year to year. In the fifty year period from 1901 to 1950, the highest annual rainfall in the district amounting to 156 per cent of the normal occurred in 1944 while the lowest annual rainfall which was only 44 per cent of the normal occurred in 1918. In the same fifty year period the rainfall in the district as a whole was less than 80 per cent of the normal in six years, two of which were consecutive. But at some of the stations, two or three consecutive years of such low rainfall have occurred twice or thrice in the fifty year period. The rainfall was less than 80 per cent of the normal for four consecutive years from 1904 to 1907 at Navapur and for 9 consecutive years from 1901 to 1909 at Nandurbar.

It will be seen from table 2 that the annual rainfall in the district was between 500 and 800 mm. (19.69" and 31.50") in 36 years out of fifty.

On an average there are about 42 rainy days (i.e., days with rainfall of 2.5 mm.— 10 cents —or more) in a year in the district. This number varies from 31 at Sakri to 58 at Navapur.

The heaviest rainfall in 24 hours recorded at any station in the district was 324.6 mm. (12.78") at Navapur on July 26, 1896.

Temperature.

There is one meteorological observatory in the district located at Nandurbar. The records of this observatory may be taken as fairly representative of the meteorological conditions in the district as a whole. From about the latter half of February, temperatures increase steadily till May which is the hottest part of the year with the mean daily maximum temperature at 40.7° C (105.3° F) and the mean daily minimum at 25.8⁰ C (78.4° F). Hot, dry winds blow during April and May and the heat is intense with the maximum temperatures going above 45° C (113.0° F) on some days. Thunder-showers occur during the afternoons and bring welcome-relief from the heat on some days. With the onset of the southwest monsoon by about the second week of June there is an appreciable drop in day temperatures and the weather is pleasant in the south-west monsoon season. By about the beginning of October when the south-west monsoon withdraws, day temperatures begin to rise and a secondary maximum in day temperature is reached in October. The night temperatures, however, steadily decrease. From November, both day and night temperatures drop rapidly till January which is the coldest month with the mean daily maximum temperature at 30.'3° C (86.5⁰ F) and the mean daily minimum at 16.2° C (61.2° F). During the cold season, cold waves which sometimes affect the district in association with western disturbances which pass across north India the minimum temperature may drop down to about 8° to 9° C (46.4° to 48.2° F).

The highest maximum temperature recorded at Nandurbar was 46.1° C (115.0° F) on May 19, 1955. The lowest minimum was 8.9° C (48.0° F) on January 10, 1954.

Humidity.

Except during the south-west monsoon season when the humidity is above 70 per cent, the air is rather dry over the district during the rest of the year. The driest part of the year is the summer season when the relative humidity is only 20 to 25 per cent in the afternoons.

Cloudiness.

During the south-west monsoon season the skies are heavily clouded to overcast. For the rest of the year skies are mostly clear or lightly clouded. During the afternoons in the latter half of summer the cloudiness is more than in the mornings.

Winds.

Winds are generally light to moderate with some strengthening in  force during the summer and monsoon seasons. During the southwest monsoon season, winds are mainly south-westerly to westerly.

In the post-monsoon season winds are light and variable in directions in the mornings and north-easterly to easterly in the afternoon. In the winter and summer seasons winds are mostly from directions between south-west and north-west, with northerly or north-easterly winds blowing on some afternoons.

Special Whether Phenomena.

In association with the westward passage of depressions from the Bay of Bengal in the south-west monsoon season and storms or depressions from the Arabian sea in the post-monsoon season, the district gets wide-spread heavy rains and strong winds. Thunderstorms occur in the summer and post-monsoon seasons. Even in the south-west monsoon season rainfall is sometimes associated with thunder.

Tables 3, 4 and 5 give the temperature and humidity, mean wind speed and special weather phenomena for Nandurbar.

TABLE No. 1

NORMALS AND EXTREMES OF RAINFALL

(a) Normal rainfall in mm, (b) Average number of rainy days (days with rain of 2.5 mm. or more). 'Based on all available data up to 1959. ┼ Years given in brackets.

continued..

TABLE No. 2

FREQUENCY OF ANNUAL RAINFALL IN THE DISTRICT
(Data 1901-'50)

TABLE No. 3

NORMALS OF TEMPERATURE AND RELATIVE HUMIDITY
(Nandurbar)

‡ Hours I. S. T.

TABLE No. 4

MEAN WIND SPEED IN KILOMETRES PER HOUR

(Nandurbar)

TABLE No. 5

SPECIAL WEATHER PHENOMENA
(Nandurbar)

TOP