Weather will likely play an important role when you plan your trip to Sylhet, 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 80°F, while the coldest months are January and December with an average of 70°F. The rainiest months in Sylhet are June, July, August, and May, with each month seeing an average of 34 inches of rainfall.