When Does Tick Season Finally End in Northern Illinois?
Should you continue being careful about encountering ticks in Northern Illinois even though we're past the halfway point of October, or has a really nasty spring and summer of ticks finally come to a close?
If you’ve spent any time outdoors in Northern Illinois this year, you’ve probably heard the same complaint over and over: “The ticks are terrible!” And you’re not wrong, 2025 has been a banner year for those tiny, unwanted, disease-carrying hitchhikers. But as we slide deeper into fall, the question everyone who spends time outdoors may be asking is: When can we finally stop worrying about ticks?
Unfortunately, there’s no single date when they all just call it quits. Ticks don’t read calendars, they follow temperatures. Once the weather consistently dips below freezing, most species go dormant, burrowing into leaf litter or soil to wait out winter. But as long as it stays above 32°F, they can stay active even in late November or early December during a mild spell.
Here's What Tick Experts Have To Say
The Illinois Department of Public Health (IDPH) says adult blacklegged ticks (the ones that can spread Lyme disease) can still be active in October through December if conditions are right. Most experts agree that tick activity in our area runs roughly March through November, with a slow tapering off in late fall. So, if you’re out raking leaves, hiking, or walking the dog on a warm day, it’s still smart to be cautious.
Here’s a quick rule of thumb:
Above freezing? Ticks are possible.
Below freezing for days in a row? They’ve gone to bed for the season.
That means for Northern Illinois residents, tick season usually winds down by mid to late November, but Mother Nature can extend it a bit if she serves up a warm snap.
Don't Pack Up Your Bug Repellent Sprays Just Yet
Keep doing quick tick checks after yard work or walks, especially on pets, and make sure to clean up piles of leaves and brush where ticks like to hide. When that first real cold snap finally hits, go ahead and breathe a sigh of relief. Your odds of finding a tick clinging to your pant leg or your pup will drop dramatically…at least until spring rolls around again. Here's more on our least favorite part of warm weather season:
Nine tick species call Illinois home, but the big three that bite humans most often are the blacklegged tick (deer tick), American dog tick, and lone star tick.
Lyme disease in Illinois is spread mainly by the blacklegged tick. It’s found in nearly every county, including most of Northern Illinois.
Tick “season” typically runs from March through November, peaking in May, June, and July.
Ticks don’t jump or fly, they “quest” by waiting on tall grass or low shrubs and latching on when you brush past.
Adult ticks can survive freezing temperatures by hiding under leaves, snow, or soil until it warms up again.
A tick usually needs to be attached for 24–36 hours to transmit Lyme bacteria, so quick removal matters.
Pets can carry ticks indoors, so check your dog or cat even if they’re just in the backyard.
Mild winters and wet summers can extend the tick season, keeping them active longer into fall.
LOOK: 11 tick-borne illnesses and what to watch out for during your outdoor adventures
Gallery Credit: Martha Sandoval
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