If you're hoping to get lost in the rain on your romantic getaway, take a look at these details about year-round temperatures in Iron Mountain: The hottest months are usually July and August, with an average temperature of 17°C, while the coldest months are February and January, with an average of -6°C. The snowiest months in Iron Mountain are January, April, March and May, with each month seeing an average of 18 cm of snowfall.