Taking into account the local weather in Grand Falls - Windsor is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually July and August with an average temp of 58°F, while the coldest months are February and January with an average of 24°F. The snowiest months in Grand Falls - Windsor are February, March, December, and January, with each month seeing an average of 15 inches of snowfall.