Weather will likely play an important role when you plan your trip to Flat, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually July and June with an average temp of 53°F, while the coldest months are January and December with an average of 9°F. The snowiest months in Flat are February, December, November, and March, with each month seeing an average of 33 inches of snowfall.