Weather will likely play an important role when you plan your trip to Roi Et, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually April and March with an average temp of 86°F, while the coldest months are January and December with an average of 77°F. The rainiest months in Roi Et are September, July, August, and May, with each month seeing an average of 11 inches of rainfall.