The National Weather Service has been keeping rainfall records in Pittsburgh since 1871. In 155 years of measuring, no August has been wetter than this one.
Nearly 7 inches of rain fell across southwestern Pennsylvania between August 1 and 22, roughly 4.5 inches above normal, with repeated flash flood warnings across Washington, Westmoreland, and neighboring counties. The bill for a month like this comes due in our streams over the next year.
What a month like this does to a watershed
Streambanks that were marginal in July are cut and slumping now. Sediment that took years to stabilize is moving again. Large woody debris has rearranged itself, sometimes helpfully, sometimes into the wrong culvert. Combined sewer systems overflowed repeatedly, which means bacteria counts in urban streams spent much of the month at levels nobody should wade in. Groups with monitoring programs should expect their late summer data to look unlike anything in their baseline.
What to do about it this month
Walk your project sites soon, camera in hand. Documenting storm damage now, while it is fresh, does two things: it builds the record that grant applications for repair work will need, and it captures the argument for the next stormwater conversation with your municipality while everyone still remembers the water in their basement.
Why it matters for the rest of us
A record that stood since 1871 is the kind of fact that gets a supervisor’s attention. Riparian buffers, floodplain reconnection, green stormwater infrastructure, all the things watershed groups have been advocating for years, just got their most persuasive month of evidence in a century and a half. Put it in every stormwater presentation this region gives for the next several years.
Rainfall figures from TribLive, August 22, 2026, with earlier coverage from the Pittsburgh Post-Gazette, August 17, 2026.
