FleaDates › Tick season › Wisconsin
Midwest · WI
When are ticks active in Wisconsin?
Ticks in Wisconsin are typically active late March to mid-November, heaviest May–Sep — and adult blacklegged ticks can surface on any mild winter day.
Ticks to know in Wisconsin
Wisconsin sits at the heart of blacklegged (deer) tick range in the upper Midwest, with the western and northern forests carrying the heaviest populations and the nymphs that spread Lyme disease most active in late spring and early summer. American dog ticks are the other common find, patrolling grassy trail margins from spring onward. Tick pressure is highest June through September, builds steadily from March through May, and leaves a thin tail into November.
Wherever the calendar sits this month, the habit that actually catches ticks is the after-walk check: ears, collar line, armpits, between the toes. Prevention plus checks beats either alone.
Month-by-month tick activity in Wisconsin
| Month | Typical activity | Average temperature |
|---|---|---|
| January | Quiet | 20.6°F |
| February | Quiet | 23.7°F |
| March | Low | 34.3°F |
| April | Moderate | 45.6°F |
| May | High | 57.2°F |
| June | Peak | 67.3°F |
| July | Peak | 71.9°F |
| August | Peak | 70.2°F |
| September | Peak | 62.7°F |
| October | Moderate | 50.5°F |
| November | Low | 37.8°F |
| December | Quiet | 26.4°F |
Estimates from NOAA U.S. Climate Normals (1991–2020), averaged across 3 weather stations near Wisconsin's larger cities, using the ~40°F activity threshold reported in published tick research. Real years run early or late with the weather.
Fleas peak later. Wisconsin flea season typically runs mid-April to late October — see the Wisconsin flea season page.
Frequently asked questions
When does tick season start in Wisconsin?
Around late March in a typical year, once temperatures clear roughly 40°F — noticeably earlier than flea season. A February thaw can bring ticks out ahead of schedule.
What ticks live in Wisconsin?
The species dog owners most often meet in Wisconsin: blacklegged (deer) tick, American dog tick. Wisconsin sits at the heart of blacklegged (deer) tick range in the upper Midwest, with the western and northern forests carrying the heaviest populations and the nymphs that spread Lyme disease most active in late spring and early summer. American dog ticks are the other common find, patrolling grassy trail margins from spring onward. Tick pressure is highest June through September, builds steadily from March through May, and leaves a thin tail into November.
Do I need tick prevention in winter in Wisconsin?
Yes. Ticks overwinter under leaf litter and snow rather than dying off, and mild spells wake them — which is why veterinary organizations recommend year-round parasite prevention. The calendar shows when pressure peaks, not when protection can lapse.
What about fleas in Wisconsin?
Fleas run on a warmer calendar — in Wisconsin that's mid-April to late October. See the Wisconsin flea season page for that month-by-month picture.