Weather is only one factor, but it can really affect your travel plans, especially when you're planning an extended stay in Iliamna. The hottest months are usually July and August with an average temp of 51°F, while the coldest months are January and December with an average of 19°F. The snowiest months in Iliamna are December, February, November, and March, with each month seeing an average of 27 inches of snowfall.