The climate of Rajasthan can be divided into four seasons: Pre-Monsoons, Monsoon, Post-Monsoon and Winter.
Pre-monsoon, which extends from April to June, is the hottest season,
with temperatures ranging from 32oC to 45oC. In
western Rajasthan the temp may rise to 48C, particularly in May and
June. At this time, Rajasthan only hill station, Mt Abu registers
the lowest temperatures. In the desert regions, the temperatures drops
in night. Prevailing winds are from the west and sometimes carry dust
storms (we call them andhi).
The second season Monsoon extends from July to September, temp drops
but humidity increases making it very un comfortable, even when there is
slight drop in the temp (35oC to 40oC). We have
about 90% of our rains in this period.
The Post-monsoon period is from Oct to December. The average maximum
temperature is 33oC to 38oC, and the minimum is
between 18oC and 20oC.
The fourth season is the winter or cold season, from January to March.
There is a marked variation in maximum and minimum temperatures, and
regional variations across the state. January is the coolest month of
the year. And temp may drop to 0oC in some cities of
Rajasthan, like Churu. There is slight precipitation in the north and
north-eastern region of the state, and light winds, predominantly from
the north and north-east. At this time, relative humidity ranges from
50% to 60% in the morning, and 25% to 35% in the afternoon.