If you're looking forward to lots of outings with your partner, take a look at these details about year-round temperatures in Priest River: The hottest months are usually July and August, with an average temperature of 18°C, while the coldest months are February and January, with an average of -2°C. The snowiest months in Priest River are January, December, February and March, with each month seeing an average of 28 cm of snowfall.