Taking into account the local weather in Pensilvania is an important factor for planning your visit, especially if you plan to spend your trip poolside. The hottest months are usually August and September with an average temp of 70°F, while the coldest months are January and December with an average of 68°F. The rainiest months in Pensilvania are October, November, April, and March, with each month seeing an average of 17 inches of rainfall.