If you’re looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Guwahati: The hottest months are usually April and May, with an average temperature of 27°C, while the coldest months are January and December, with an average of 20°C. The rainiest months in Guwahati are July, August, June and September, with each month seeing an average of 615 mm of rainfall.