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Philadelphia · PA
When does flea season start in Philadelphia?
Flea season in Philadelphia typically runs late March to mid-November, peaking May–Sep.
Ticks in Philadelphia
Local tick activity typically runs late February to mid-December, heaviest Apr–Oct. The species to know in Pennsylvania: blacklegged (deer) tick, American dog tick, lone star tick.
More on species and timing: Pennsylvania tick season.
Numbers come from NOAA U.S. Climate Normals (1991–2020) recorded at PHILADELPHIA NE AP — a climate-based estimate; real years wobble.
Frequently asked questions
When does flea season start in Philadelphia?
Around late March in a typical year, once local averages hold around 50°F. A warm spring pulls it earlier — prevention shouldn't wait for the calendar.
Is flea season in Philadelphia different from the rest of Pennsylvania?
Not meaningfully — Philadelphia tracks the Pennsylvania statewide estimate closely. Both are climate-based estimates, so treat the edges as fuzzy, not exact.
Do dogs in Philadelphia need prevention outside flea season?
Yes — vets recommend year-round parasite prevention regardless of the local calendar. Indoor fleas ignore the weather entirely, and ticks in Pennsylvania are typically active early March to early December, a longer window than fleas get.