Taking into account the local weather in Granby 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 57°F, while the coldest months are January and December with an average of 18°F. The snowiest months in Granby are December, January, February, and March, with each month seeing an average of 24 inches of snowfall.