Weather will likely play an important role when you plan your trip to Diu, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually May and April with an average temp of 85°F, while the coldest months are January and February with an average of 76°F. The rainiest months in Diu are July, September, August, and June, with each month seeing an average of 9 inches of rainfall.