Pittsburgh has a humid continental climate (Köppen Dfa/Dfb), with warm, humid summers and genuinely cold winters. Its defining trait, though, is grey: tucked downwind of the Great Lakes and wrapped in Appalachian moisture, the city is one of the cloudiest major metros in the country, seeing relatively few clear days — especially from late fall through mid-winter.
Summers are warmest in July, with highs averaging the low-to-mid 80s, muggy afternoons, and regular thunderstorms rolling through the river valleys. Winters are coldest in January, with lows around the low 20s and snow a frequent visitor from December into March — roughly 28 inches a year at the airport, and more across the higher ground of the surrounding ridges and the Laurel Highlands. Precipitation is frequent but often light, totalling about 38 inches over the year.
The three rivers are central to the city's weather story. The confluence of the Allegheny, Monongahela, and Ohio makes Pittsburgh prone to flooding — from the historic 1936 flood to modern flash floods when heavy rain meets steep, narrow valleys or combines with spring snowmelt. Heavy lake-effect snow, by contrast, mostly stays north in Erie and northwest PA; Pittsburgh only occasionally catches the edge of a band.
Climate normals (approximate)
- Warmest month: July — average high around 83 °F
- Coldest month: January — average low around 21 °F
- Annual precipitation: roughly 38 inches
- Annual snowfall: about 28 inches (more in the hills)
- Cloud cover: among the cloudiest large U.S. cities
- Climate type: humid continental (Köppen Dfa/Dfb)
Common questions
- Why is Pittsburgh so cloudy?
- It sits downwind of the Great Lakes, which generate persistent low cloud, with Appalachian moisture adding to it. The effect is strongest from November through January.
- Does Pittsburgh get lake-effect snow?
- Mostly no — heavy lake-effect snow targets Erie and northwest Pennsylvania. Pittsburgh is usually south of the main belt and only occasionally clipped by lighter bands.
- How serious is the flood risk?
- Real. The three rivers plus steep valleys mean both river flooding and flash flooding are possible after heavy or prolonged rain, particularly in spring.
Figures are long-term climate normals (roughly the 1991–2020 reference period) and are meant for context. The live readings at the top of this page always reflect current conditions.