If you’re looking forward to lots of outings with your partner, check out these details about year-round temperatures in Greybull: The hottest months are usually July and August with an average temp of 70°F, while the coldest months are February and January with an average of 26°F. The snowiest months in Greybull are February, April, March, and October, with each month seeing an average of 13 inches of snowfall.