December, January and February can be brutally cold, but the chilly air doesn't scare the Pittsburghers, and it shouldn't keep you from visiting altogether. You'll find the major attractions less crowded, and it's an especially good time to take advantage of the arts scene, as it's better to be indoors. When the snow falls, the landscape is transformed. There are several ski resorts located within a short drive of the city, so you can make the most of the snow and hit the slopes. You'll also find no shortage of holiday activities, from parades to New Year's Eve celebrations.
Spring is generally cool and sometimes rainy, and with luck you can catch one of Pittsburgh's beautiful thunderstorms over the rivers (hopefully not while you're trying to get on your flight home). The rainiest month of the year, surprisingly, is June, so be careful to have backup plans for outdoor activities. As the city wakes from its winter slumber, you'll find the Cultural District at its finest, catering to the crowds who are finally ready to get out of the house again.