Taking the local weather in Ketchum into account is an important factor for planning your visit, especially if you plan to spend your trip by the pool. The hottest months are usually July and August, with an average temperature of 16°C, while the coldest months are December and January, with an average of -7°C. The snowiest months in Ketchum are February, January, March and December, with each month seeing an average of 41 cm of snowfall.