The climate of Pennsylvania is diverse due to the multitude of geographic features found within the state. Straddling two major climate zones, the southeastern corner of Pennsylvania has the warmest climate. A portion of Greater Philadelphia lies at the southernmost tip of the humid continental climate zone, with the city proper being in the humid subtropical climate zone. Still, Philadelphia features colder, snowier winters than most locations with a humid subtropical climate. Moving west toward the mountainous interior of the state, the climate becomes markedly colder, the number of cloudy days increases,[1] and winter snowfall amounts are greater.
Using the January freezing isotherm, the humid subtropical climate (Cfa) only exists in parts of Greater Philadelphia and low-lying areas of the lower Susquehanna Valley from Harrisburg downriver. Pennsylvania's hardiness zone ranges from 5a in high-elevation areas to 7b in parts of Delaware and Philadelphia Counties.
- ^ The Pennsylvania State Climatologist. Annual Average Number of Cloudy Days In Pennsylvania. Archived 2008-08-05 at the Wayback Machine Retrieved on 2008-01-28.