You might spend a lot of your vacation inside, but if you're planning to venture beyond the casino, looking at local weather trends is a good idea. The hottest months are usually July and August with an average temp of 72°F, while the coldest months are January and December with an average of 31°F. The snowiest months in Salt Lake City are April, January, March, and February, with each month seeing an average of 10 inches of snowfall.