Taking into account the local weather in Grassy Butte 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 68°F, while the coldest months are January and February with an average of 19°F. The snowiest months in Grassy Butte are October, March, February, and December, with each month seeing an average of 10 inches of snowfall.