Pennsylvania Mosquito Forecast
Pennsylvania sees moderate mosquito pressure, shaped by a temperate, humid climate and about 43" of rain a year. Activity builds through the warm months and runs from May through September.
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When is mosquito season in Pennsylvania?
Pennsylvania's mosquito season runs from May through September. Activity ramps up once overnight lows hold above about 50°F, and surges in the two to three days after rain, when fresh standing water triggers a new hatch. Hot, dry stretches briefly knock numbers back before the next rain refills the breeding sites.
Where are mosquitoes worst in Pennsylvania?
Within Pennsylvania, the most consistent pressure tends to land around Philadelphia, Pittsburgh, and Allentown. Urban heat plus abundant standing water — storm drains, retention ponds, backyards — concentrates activity around these metros. Anywhere near rivers, marshes, lakes, or recent flooding will read higher than the surrounding area — exactly the kind of local detail the live map above is built to show.
How the Pennsylvania forecast works
MosquitoCast estimates Pennsylvania's mosquito activity from live weather — temperature, humidity, wind, and recent rainfall — layered on the area's long-term rainfall climate, elevation, and terrain, and refreshed every day from NOAA's forecast data. It's the same model nationwide, so the reading for Pennsylvania is directly comparable to anywhere else in the country.