The national picture
Flea season, state by state
The same flea lives very different lives in Tampa and in Fargo. This map colors each state by how much of the year fleas stay active there — click through for the month-by-month calendar.
Every state's flea calendar
- Alabama — late January to mid-December
- Alaska — mid-May to mid-September
- Arizona — early February to early December
- Arkansas — early March to late November
- California — year-round
- Colorado — mid-April to late October
- Connecticut — early April to early November
- Delaware — late March to mid-November
- Florida — year-round
- Georgia — late January to late December
- Hawaii — year-round
- Idaho — mid-April to late October
- Illinois — early April to early November
- Indiana — late March to early November
- Iowa — early April to late October
- Kansas — late March to early November
- Kentucky — mid-March to mid-November
- Louisiana — year-round
- Maine — late April to mid-October
- Maryland — late March to mid-November
- Massachusetts — mid-April to late October
- Michigan — late April to late October
- Minnesota — late April to mid-October
- Mississippi — late January to late December
- Missouri — late March to mid-November
- Montana — late April to mid-October
- Nebraska — early April to late October
- Nevada — mid-March to mid-November
- New Hampshire — mid-April to late October
- New Jersey — late March to mid-November
- New Mexico — mid-March to mid-November
- New York — mid-April to early November
- North Carolina — late February to late November
- North Dakota — late April to mid-October
- Ohio — early April to early November
- Oklahoma — late February to late November
- Oregon — late March to early November
- Pennsylvania — early April to early November
- Rhode Island — mid-April to early November
- South Carolina — early February to mid-December
- South Dakota — late April to mid-October
- Tennessee — late February to late November
- Texas — year-round
- Utah — late March to early November
- Vermont — late April to mid-October
- Virginia — mid-March to late November
- Washington — early April to late October
- West Virginia — late March to mid-November
- Wisconsin — mid-April to late October
- Wyoming — early May to mid-October
Ticks run on an earlier, longer calendar than fleas — many wake around 40°F. See tick season by state.
Frequently asked questions
Which states have flea season all year?
Along the Gulf Coast, in the Southeast lowlands, in Hawaii, and in much of coastal California, average temperatures never fall low enough to shut fleas down — the calendar there is about peaks, not an on/off switch. The deep-blue states on the map get real winters that knock outdoor fleas back for months.
When does flea season start in the northern states?
Typically once average temperatures hold around 50°F — mid-spring in most of the Midwest and Northeast, and as late as May in the high Mountain West. Each state page shows the estimated start and end for that climate.
Does a hard winter mean I can stop flea prevention?
No — and that's not just caution talking. Fleas overwinter beautifully indoors on pets and in bedding, so a January infestation in Minnesota is a Tuesday, not a paradox. Veterinary organizations recommend year-round prevention everywhere; the season pages tell you when outdoor pressure peaks on top of that baseline.
How are these season windows estimated?
From NOAA U.S. Climate Normals (1991–2020): monthly average temperatures near each state's major cities, crossed with flea activity thresholds from published veterinary and entomology research. They're climate-based estimates — real years run early or late with the weather.