Taking into account the local weather in Nampa 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 59°F, while the coldest months are February and December with an average of 12°F. The snowiest months in Nampa are January, October, February, and November, with each month seeing an average of 8 inches of snowfall.