The climate of Rajasthan can be categorised into four seasons: Pre- Monsoon, Monsoon, Post-Monsoon, and Winter. Pre-Monsoon: Rajasthan experiences this season from the month of April to June. It is the hottest season with temperatures ranging from 32°C to as high as 45°C. Mount Abu registers the lowest temperatures at this time. In the desert regions, the temperature decreases as night falls and rises up again during the day. Steady winds emerge from the west and sometimes carry dust storms. The only benefit is that the winds are usually followed by a slight reduction in temperatures, and sometimes by light showers.
Monsoon: This season can be experienced during the late June in the eastern and south-eastern regions of the state, finally falling in the desert zones during the mid-July. It is preceded by dust and thunderstorms. Unless the rains are in abundant amount, the monsoon is accompanied by a slight decrease in temperatures, with average maximum temperatures between 29.5° C to 32.2°C in the south and south-east of Rajasthan and an average of above 37°C in the north and north-western regions. Over 90% of Rajasthan’s precipitation occurs during the monsoon period and humidity is greatest at this time, particularly in the month of August, although the humidity is less evident in the desert zone
Post Monsoon: The monsoon generally comes to an end by mid-September, after which a second hot season follows, known as post-monsoon. This season has relatively consistent temperatures registered across the entire state. During the month of October, the average maximum temperature is usually between 33°C to 38° C and the average minimum temperature is between 18°C and 20° C.
Winters: Rajasthan experiences the winter season from the month of December to March. The average maximum and minimum temperatures during this season vary in different regions, across the state. January happens to be the chilliest month of the year in Rajasthan.
Average temperatures at the following centres are as follows (minimums in brackets):-
Bikaner 22°C (9°)
Jaipur 22.8° C (9°)
Ajmer 22.8° (7.7°C)
Jodhpur 24.4°C (9°C)
Kota 25°C (10.5°C)
A slight precipitation in the north and north-eastern regions of the state is experienced which is accompanied by 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.
There is a wide variation in the distribution of rainfall across the state, with a reduction in the volume of rain as you proceed further west. In the south-east region, over 1500mm can be expected, with most rain (about 90% of the annual rainfall) falling during the monsoon period (mid -June to mid -September ), whereas an average of 55 days of rain may be registered at the western extremity of Rajasthan, less than 100 mm in any one year, and rainfall is received on an average of only 15 days in the year.