Philadelphia is a typically temperate city on the east coast of the U.S.  Like many places in the northeast U.S., the weather can be very changeable.  Usually Philly is cold in the winter (30s-40s deg F/2 - 5 deg C) and hot in the summer (80s - 90s F/26 - 33 degC).  The past few years, however, have seen milder winters.   

Winter

During the holiday season, Philadelphia has many festive displays including the Macy's holiday lights show.  In December, adults and children alike enjoy the Philadelphia Ballet's performance of the Nutcracker.  On New Year's day, Philadelphia hosts the very unique Mummer's Parade.

Spring

The city has a beautiful spring that lasts several weeks with many flowering trees in Center City.  Garden enthusiasts should visit the first week of March to enjoy the Philadelphia Flower Show, the world's largest indoor gardening exhibition.  In late March to early April, a variety of Japanese cherry trees bloom along the Schuykill River and in areas of Fairmount Park, and a cherry blossom festival is held at the Horticultural Center.  In spring, there is plenty of activity on the Schuykill River, including the Stotesbury Regatta and Dad Vale Regatta boat races, and in early June, the Manayunk Bike race brings many spectators. 

Summer

The summer months are prime tourist time and you'll find long lines at the major historic attractions.   Philadelphia hosts a week-long "Welcome America" celebration in early July, including an impressive fireworks display and free concert near the Philadelphia Museum of Art for July 4th.  During the summer months, outdoor concerts can be enjoyed at the Mann Music Center, and Penns Landing on the Delaware River is lively with concerts and festivals.

Fall

 Early fall is a nice time weatherwise and the city is lively with the arrival of college students back on campus.  William Penn's "greene country towne" can also impress with fall colors -- especially in Fairmount Park.  The theatre season starts in the fall, so it's also a good time for cultural travel.  Depending on your tastes, any time of year can be fun to explore the restaurants, museums, neighborhoods, and shops of the city.  In October, take time to visit "Terror Behind the Walls," a haunted house attraction staged annually at the historic Eastern State Penitentiary.  Philadelphia also hosts an elaborate Thanksgiving Day parade.

If you don't mind walking in a city in a variety of temperature regimes, then come any time. 

Philadelphia Weather