October to February is the best window. Temperatures are bearable (daytime highs 25–30°C, cool nights), the post-monsoon landscape is green, and migratory birds are on the Lonar lake. December and January are the most comfortable.
March to May is dry and very hot — temperatures regularly above 40°C — and the lake levels drop. Travel is uncomfortable but possible if you can move in the early morning.
June to September brings the monsoon, which can wash out roads to Lonar and make the crater paths slippery. The landscape is at its greenest, but practically more difficult.