Planning for the weather is a good way to make your trip to Ranchi relaxing and enjoyable, especially when you're splurging. The hottest months are usually May and April with an average temp of 85°F, while the coldest months are January and December with an average of 66°F. The rainiest months in Ranchi are August, July, September, and June, with each month seeing an average of 13 inches of rainfall.