April to June are the summer months in Jaisalmer. The temperature during these months is hot, dry and very harsh. Sightseeing during this season should never be an option. It is advisable to avoid visiting Jaisalmer during this season. The maximum daytime temperature can rise to 45 – 50 degrees Celsius. It is, therefore, absolutely not the best weather to visit Jaisalmer. If you still don't have any choice regarding this and you will be in the city during this time then keep yourself hydrated and try to go for sightseeing in the evenings. As the evenings are a bit pleasant.
October till early March, as mentioned above, is the winter season in Jaisalmer, and hence the best season to visit Jaisalmer. During these months, the temperature drops till 2-3 degrees Celsius and sightseeing, camping, desert safaris, become pleasurable. It is undoubtedly the best time to visit for Jaisalmer desert safari and experiencing camel ride during this season is a must. Also, one of the best places to visit there is the Jaisalmer Sam Sand Dunes and the city also gets prepped up for its annual Jaisalmer Desert Festival which shouldn't be missed.
Jaisalmer experiences monsoon during July to September. Monsoon months are also the good time to visit the city in case you are not able to visit during the winter months. The city witnesses very less rainfall and at times there isn't any rain as well. The limited showers also increase the humidity in air. These very less rainfall provides no respite from the temperature. But the evenings are pleasant and comfortable. One can explore the city and enjoy the mesmerizing sunset during this time.