Philadelphia’s [1] four distinct seasons offer very different experiences and activities. Summers are often very hot and humid, while winters can be extremely cold. Fall and spring are generally mild and pleasant. While each season offers its own advantages, you will need to plan your day and dress accordingly if you visit in one of the more extreme seasons.
Average temperatures in July range 67–86°F (20–30°C), but severe heat waves can bring temperatures up to 95°F (35°C) with the heat index as high as 110°F (43°C). While this usually only lasts for a few days each summer, it is very unpleasant to do anything outdoors during a heat wave. In January, the average temperature is 23–38°F (3–5°C), with occasionally frigid temperatures, severe snowfall, and icing that can make driving dangerous. This is the exception rather than the rule, however, and on most winter days, bundling up in warm clothes will make it possible to get between destinations without too much trouble.
The classic Northeast Fall is quite beautiful in Philadelphia [1], complete with leaves changing colors and falling from the trees as the heat of summer gives way to cooler weather. Spring is mostly filled with many perfectly comfortable, pleasant days. Rainfall is moderate with 42 inches annually. Seasonal snowfall varies from a light dusting to the occasional blizzard with an average of 21 inches a year. Precipitation is generally spread throughout the year, so a light rain jacket will come in handy. A local current weather report and forecast is available 24 hours a day by calling 215/936-1212.
Links:
[1] http://www.moon.com/destinations/philadelphia/discover-philadelphia