Philadelphia can be really pleasant this time of year. (It can also be snowy, cold, and icy.) Also, "pleasant" in this context means "much less snowy, cold, and icy than the frozen wastes of upstate PA."

In any case, enjoy your visit to one of my favorite places. The Art Museum is definitely worth a look, if you have spare time. Or the Rosenbach Museum if you like book manuscripts. Or (sorry, I am in tour guide mode.)