Most ticks can survive temperatures well below freezing, so cold alone is not a reliable way to kill them. The deer tick (also called the blacklegged tick) starts dying around 14°F (-10°C), but some individuals survive all the way down to -7°F (-21.7°C) by pulling water out of their cells before ice crystals can form. In practice, a single cold snap rarely wipes out a tick population.
Lethal Temperatures by Species
The deer tick is the most studied species for cold tolerance because it carries Lyme disease and stays active later into fall and winter than other common ticks. Researchers at the Tick Research Lab of Pennsylvania found that 14°F (-10°C) is the temperature at which roughly half of a deer tick population dies. That sounds cold enough to matter, but the hardiest individuals can push their survival limit much further, down to about -7°F (-21.7°C). They manage this by producing small protective molecules, including glycerol and certain sugars, that act like antifreeze. As concentrations of these molecules rise inside the tick’s body, the temperature at which its tissues actually freeze drops lower and lower.
Other species, like the American dog tick and the lone star tick, handle cold differently. They tend to become inactive and seek shelter earlier in the year, retreating underground or into leaf litter before temperatures drop sharply. They’re less cold-hardy overall but also less exposed, because they simply aren’t out in the worst of winter.
Why Winter Doesn’t Kill Most Ticks
Even in places where air temperatures plunge well below zero, ticks at ground level experience something much milder. Leaf litter and snow act as insulation, creating a microclimate that stays significantly warmer than the air above it. Research from the University of Maine tested deer tick survival across sites ranging from southern to northern Maine, where winters are brutal. Overwinter survival was consistent across all sites, even in the coldest parts of the state, as long as there was adequate leaf litter and snowpack.
This means the number on your thermometer doesn’t tell the full story. A week of -15°F air temperatures might sound lethal, but if there’s a few inches of snow on a layer of fallen leaves, ticks beneath that blanket may be sitting in conditions closer to 20°F or 25°F. The insulation effect is so strong that researchers believe it’s enabling deer ticks to expand their range further north as climate change brings wetter winters with more snow cover.
Ticks Stay Active in Surprisingly Cool Weather
Cold weather slows ticks down, but it doesn’t stop them as early as most people assume. Deer ticks actively search for hosts (a behavior called questing) at temperatures as low as 50°F (10°C). Lab studies show they quest most at moderate temperatures around 68°F, but females in particular remain active even in cool conditions. This is why deer tick bites happen on mild winter days when people let their guard down, thinking tick season is over.
A warm spell in January or February can bring deer ticks right back to the tips of grass blades and low vegetation. If the ground isn’t frozen solid and the temperature creeps above that low-40s to 50°F range, adult deer ticks will resume questing.
Your Freezer Won’t Reliably Kill Ticks
A standard home freezer runs at about 0°F (-18°C), which falls within the survival range for the hardiest deer ticks. The University of Rhode Island’s TickEncounter program states plainly that adult deer ticks are not killed by freezing temperatures. While extended time in a freezer might kill some ticks, it’s not a method you can count on, and there’s no well-established duration that guarantees success.
Heat Works Better Than Cold
If you’re trying to kill ticks on clothing or gear after spending time outdoors, heat is far more effective than cold. Ticks survive cold and warm water washes without difficulty. Running clothes through a washing machine on cold or warm settings essentially gives the ticks a bath.
The dryer is what actually kills them. Ten minutes on high heat is enough for lightweight clothing. For thicker items like jeans, sweatshirts, towels, or socks, 20 to 30 minutes on high heat is a safer bet. Even ticks that survive a full wash cycle are very unlikely to survive the dryer. If your clothes are already dry when you come inside, you can skip the wash entirely and toss them straight into the dryer on high.
This approach is more practical and more reliable than any cold-based method. Ticks evolved to survive freezing winters. They did not evolve to survive sustained dry heat above 130°F, which is well within the range of a household dryer on its high setting.