Tick season is already underway across most of the United States. While many people think of ticks as a summer problem, these parasites can be active any time temperatures climb above freezing, and peak activity spans from April through September in most regions. The real answer, though, depends on where you live, what species of tick is nearby, and what life stage it’s in.
When Tick Season Starts and Ends
Ticks become active when temperatures consistently stay above about 4°C (39°F). Some species need it even warmer, around 12°C (54°F), before they start seeking a host. That means in much of the country, tick season begins in March or April and runs through October or November. But “tick season” is really a rolling window that shifts by region.
Spring marks the beginning of what most people recognize as tick season nationwide. In the Northeast and upper Midwest, activity ramps up in April and stays high through summer. The Southeast sees earlier starts, sometimes in February, because mild winters let ticks stay active longer. On the West Coast, the pattern flips in an interesting way: western blacklegged ticks are most active during the cooler, wetter months from fall through early spring, with peak reports in California, Oregon, and Washington during winter.
Fall catches many people off guard. Adult blacklegged ticks (commonly called deer ticks) surge in October and November across the Northeast, often appearing right after the first frost leads people to assume the risk has passed. This second wave of activity is driven by adult ticks that are larger, easier to spot, but still fully capable of transmitting disease.
Why Summer Is the Most Dangerous Window
The highest risk of tick-borne illness actually comes from nymphal ticks, the juvenile stage between larva and adult. In the upper Midwest, nymphs are most active from May through August, with peak activity in June. This pattern holds across much of the eastern United States.
Nymphs are roughly the size of a poppy seed, making them extremely difficult to see on your skin or clothing. Because they’re so small and their bites are painless, people often never notice them. That gives the tick more time to feed, and longer feeding time increases the chance of disease transmission. This is why the bulk of Lyme disease cases trace back to nymph bites in late spring and early summer rather than to the larger, more visible adult ticks people encounter in fall.
Ticks Don’t Disappear in Winter
One of the most persistent misconceptions about ticks is that freezing temperatures kill them. Adult blacklegged ticks survive freezing just fine. They become dormant when the ground is frozen or when they’re buried under snow, but the moment both the ground thaws and the air temperature rises above freezing, they can resume host-seeking. Even a brief January warm spell can bring ticks out in northern states.
The practical test is simple: if the ground where you’re walking isn’t frozen and the thermometer reads above 32°F, ticks could be active. This is especially relevant during increasingly common mid-winter thaws, when hikers and dog walkers venture out without thinking about tick exposure.
Humidity Matters as Much as Temperature
Temperature gets most of the attention, but humidity is arguably the more critical factor for tick survival. Blacklegged ticks need a relative humidity of at least 80% to avoid drying out during their off-host periods. This is why ticks concentrate in shaded, moist environments: leaf litter on forest floors, tall grass at woodland edges, and overgrown brush.
Open landscapes like mowed lawns, sandy areas, and pine forests with sparse ground cover support far fewer ticks because the air near the ground dries out too quickly. Ticks can push through short periods of hot, dry weather if they have access to dense vegetation where they can retreat to rehydrate. But prolonged drought genuinely suppresses tick populations in exposed areas.
Tick-Borne Disease Is Increasing
The stakes of tick season have been climbing. New York State provides a stark example: Lyme disease incidence outside New York City jumped from 37.2 cases per 100,000 residents in 2020 to 164.8 per 100,000 in 2024, a more than fourfold increase. The state reported 18,704 confirmed or probable Lyme cases in 2024 alone. Babesiosis, a tick-borne infection that attacks red blood cells, nearly doubled in incidence over the same period, reaching 670 cases.
These increases reflect a combination of expanding tick habitat, milder winters that let more ticks survive year to year, and growing deer populations that sustain adult ticks. The geographic range of blacklegged ticks has been steadily pushing northward and westward, bringing Lyme disease risk to areas that were historically considered safe.
Reducing Your Risk During Peak Months
The most effective protection is a daily tick check after spending time outdoors, especially from May through July when nymphs are at their peak. Focus on warm, hidden areas of the body: behind the ears, along the hairline, in the armpits, behind the knees, and around the waistband. Showering within two hours of coming indoors has been shown to help wash off unattached ticks.
Treating clothing and gear with permethrin (a spray available at most outdoor retailers) kills ticks on contact and lasts through several washes. Wearing light-colored clothing makes ticks easier to spot. Tucking pants into socks looks odd but creates a physical barrier that forces ticks to crawl on the outside of your clothes where you can see them.
If you find an attached tick, remove it with fine-tipped tweezers by grasping as close to the skin as possible and pulling straight up with steady pressure. The risk of disease transmission is low if the tick has been attached for less than 24 to 36 hours, which is another reason daily checks are so valuable. Save the tick in a sealed bag or photograph it, since identifying the species can help a healthcare provider assess your risk if symptoms develop later.