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Northeast · VT
When does flea season start in Vermont?
Flea season in Vermont typically runs late April to mid-October, with the heaviest pressure Jun–Sep. Outside that window outdoor fleas slow down — they don't disappear.
The Vermont flea picture
Vermont's deep winters — January averages around 19°F — hold outdoor fleas to a tight late-April-to-mid-October window, with June through September the busy months. The Champlain Valley around Burlington warms earlier in spring than the higher Green Mountain towns, giving valley dogs a slightly longer season. But no Vermont winter reaches the fleas living behind your baseboards; a heated farmhouse is midsummer as far as a flea is concerned, and vets here still advise prevention without a seasonal break.
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 Vermont
| Month | Typical pressure | Average temperature |
|---|---|---|
| January | Quiet | 18.8°F |
| February | Quiet | 20.9°F |
| March | Quiet | 30.1°F |
| April | Low | 43.3°F |
| May | Moderate | 55.9°F |
| June | High | 64.7°F |
| July | Peak | 69.5°F |
| August | Peak | 67.8°F |
| September | High | 60.1°F |
| October | Low | 47.9°F |
| November | Quiet | 36.8°F |
| December | Quiet | 25.7°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 2 weather stations near Vermont'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 Vermont — check the city closest to you:
Ticks are a different calendar. In Vermont tick activity typically runs early April to mid-November — see the Vermont tick season page.
Frequently asked questions
When does flea season start in Vermont?
Around late April 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 Vermont?
Outdoor flea pressure typically fades around mid-October, 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 Vermont?
Yes — veterinary organizations recommend year-round prevention everywhere, Vermont 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 Vermont?
Ticks run on their own, earlier calendar — in Vermont that's early April to mid-November. See the Vermont tick season page for the month-by-month picture and the species involved.