Taking into account the local weather in Lammi is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually July and August with an average temp of 59°F, while the coldest months are January and February with an average of 25°F. The snowiest months in Lammi are January, March, December, and April, with each month seeing an average of 13 inches of snowfall.