Weather will likely play an important role when you plan your trip to Kolkata, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and May with an average temp of 87°F, while the coldest months are January and December with an average of 73°F. The rainiest months in Kolkata are August, July, September, and June, with each month seeing an average of 13 inches of rainfall.