If you’re hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Ranchi: 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.