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Southeast · MD
When does flea season start in Maryland?
Flea season in Maryland typically runs late March to mid-November, with the heaviest pressure May–Oct. Outside that window outdoor fleas slow down — they don't disappear.
The Maryland flea picture
Maryland's flea year is quiet outdoors through the cold of January and February, stirs by late March, then runs hard from June through September as summer averages reach the upper 70s statewide. The Eastern Shore around Salisbury stays humid enough to stretch both shoulder seasons. None of that matters to fleas established inside a rowhouse or farmhouse, though — they keep their own calendar, which is why prevention stays on the schedule all twelve months.
One thing that's true in every state: indoor fleas are year-round everywhere. A heated house in January is a fine flea nursery, which is why the calendar above describes outdoor pressure — not whether fleas are possible.
Month-by-month flea pressure in Maryland
| Month | Typical pressure | Average temperature |
|---|---|---|
| January | Quiet | 35.6°F |
| February | Quiet | 37.7°F |
| March | Low | 44.8°F |
| April | Moderate | 55.1°F |
| May | High | 64.1°F |
| June | Peak | 73.1°F |
| July | Peak | 78.1°F |
| August | Peak | 76°F |
| September | Peak | 69.5°F |
| October | High | 58°F |
| November | Low | 47.6°F |
| December | Quiet | 39.6°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 2 weather stations near Maryland's larger cities, with activity thresholds from published veterinary and entomology research. Real years run early or late with the weather.
Flea season near you
Climate shifts even within Maryland — check the city closest to you:
Ticks are a different calendar. In Maryland tick activity typically runs mid-February to late December — see the Maryland tick season page.
Frequently asked questions
When does flea season start in Maryland?
Around late March in a typical year, once average temperatures hold around 50°F — the point where fleas begin reproducing in earnest outdoors. Warm springs pull that earlier, which is a good argument for not waiting.
When does flea season end in Maryland?
Outdoor flea pressure typically fades around mid-November, when sustained cold shuts down reproduction outside. Indoors is another story — heated homes stay flea-friendly all winter.
Does my dog need flea prevention in winter in Maryland?
Yes — veterinary organizations recommend year-round prevention everywhere, Maryland included. Fleas overwinter indoors on pets and in bedding regardless of the weather outside, and a warm snap can restart outdoor activity early. The season calendar tells you when to be extra vigilant, not when to stop.
What about ticks in Maryland?
Ticks run on their own, earlier calendar — in Maryland that's mid-February to late December. See the Maryland tick season page for the month-by-month picture and the species involved.