Check out Climate in Rajasthan under our article
Weather & Climate in Rajasthan, India.

Owing
to a varied topography the state of Rajasthan observes wide variation in
the climate throughout. Including parts of the Thar Desert or the Great
Indian Desert, Western Rajasthan is relatively dry and infertile. The
southwestern part of the state, on the other hand is more fertile,
wetter and hilly.
A wide range of differences in temperature can also be observed
throughout Rajasthan. The average temperature of the state during winter
can range somewhere between 8° to 28° C whereas during
summers, the temperature may go as high as 50° from 25° C.
These temperature differences also bring about a steady variation in the
average rainfall of the state. Where the western deserts get a 100 mm or
4 inches of annual rainfall, the southeastern part of the state receives
650 mm or 26 inches annually. Most of this rain falls during the monsoon
season between July to September. Rajasthan is known for the most
scorching summer and the most humid monsoon thus leaving winter to be
the best time to travel to Rajasthan. Extending from December to March,
winter is the most pleasant season in Rajasthan. January here is the
coolest month of the year with the temperature going as down as zero
degrees at some places like Churu.