Climate of Pennsylvania

The climate of Pennsylvania is diverse due to the multitude of geographic features found within the state.

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.

[2] Tropical cyclones normally threaten the states during the summer and fall, with their main impact being rainfall.