The nature of climate of Rajasthan is well understood with reference to three seasons:
1. Summer Season (March to Mid June)
2. Rainy Season (Mid-June to September)
3. Cold/Winter Season (October to February)
1. Summer Season (March to Mid June):
It begins in March when the sun, at this time is in Northwards direction and the temperature continues rising steadily. During May-June months the whole of Rajasthan experiences high temperature. The temperature touches 40°C especially in Jaisalmer, Barmer, Bikaner, Jodhpur, and Churu districts of Western Rajasthan. In the eastern Rajasthan, the districts of Jaipur, Dausa, Alwar, Sikar, Ajmer, Tonk, Chittorgarh, Dungarpur and Banswara, temperature varies between 30°C to 40°C.
In the elevated parts of the southern Aravalli, temperature is less because of high altitude. Even Hadauti experiences heat and the temperature remains between 36°C to 40°C. It is a period of hot and sandy winds. In the arid regions, temperature falls. There is a less of moisture in the air and the whole state in the grip of heat.
2. Rainy Season (Mid-June to September):
When the whole state is in the grip of scorching heat by mid- June, there occurs a change in the air pressure and direction of the winds. At the same time the monsoon winds arise from the Indian ocean. By the end of June or the first week of July the monsoons become active in the south and south-east and eastern Rajasthan. Rajasthan, comparatively gets less of monsoon rains because:
1. The Aravalli mountain ranges lie parallel to the monsoon branch of the Arabian sea. Thus the monsoons without being intercepted, pass over Rajasthan without giving rains.
2. The moisture laden monsoons from the Bay of Bengal become weak by the time they reach Rajasthan.
3. Rains are also adversely affected due to comparatively less height of the Aravalli mountain ranges and scarce vegetation. Rajasthan gets rains mostly from June to September.
The Western Rajasthan is Marusthali. Here the rainfall is less than 40 cm. On the contrary the eastern and south¬eastern areas get heavy rainfall. The regions surrounding Abu Mountains get maximum rainfall upto 150 cm. Kota, Jhalawar Baran,Chittorgarh and Sirohi receive mean annual rainfall of 90 cm. The districts getting minimum rainfall— between 10 cm to 25 cm in Rajasthan — are Jaisalmer, Barmer and Ganganagar.
3. Cold/Winter Season (October to February):
The rainy season does not terminate abruptly. It starts retreating from October. During this period the maximum temperature is recorded between 30° C to 50° C and minimum upto 20° C. While retreating, the monsoons shower lightly over some parts.
In fact, the Winter season begins in Rajasthan in December, because this is the time when the sun is in southward direction. The North-West cool winds start blowing over Rajasthan.
At the same time the mediterranean cyclones enter the state, bringing some rainfall known as the Mawath. This rainfall is very useful for the Rabi crops. In the month of January, the Rainy season is in its full swing. The temperature varies between 5° C to 15° C. Temperature in Churu, Falaudi touches zero degree and Barmer, Kota, Bundi and Southern Madhopur districts, during the same period, have more than 10°C temperature.
