Bitter cold weather is about to sweep through Maine, the kind of cold that can quickly numb fingers and toes and freeze exposed skin.

A female deer tick. This week’s deep freeze won’t be enough to make a dent in the population, experts say.  Gregory Rec/Staff Photographer

It’s also the kind of cold that – under precisely the right conditions – could take a bite out of Maine’s tick population. But those hoping for a tick die-off this week are going to be disappointed, experts say, in part because there’s just enough snow on the ground to protect the irksome arachnids.

Friday night temperatures in the Portland area could fall to 18 below zero, according to the National Weather Service, and the high temperature on Saturday may not reach 10 degrees. A low of minus 18 would make it the coldest February day in Portland since Feb. 23, 1972.

“We could potentially have a top 10 coldest day for February on record,” said Hunter Tubbs, a meteorologist with the National Weather Service in Gray.

Ticks, which transmit diseases such as Lyme, Powassan and babesiosis, can be killed by extreme cold or dry weather. But this week’s deep freeze is not going to be enough to make a dent in the population, according to experts. The snow covering the ground across the state right now is expected to act like a blanket and keep ticks alive until it warms up again next week.

“I don’t think this cold weather coming up is going to have much of an impact on tick populations at all,” said Griffin Dill, who runs the University of Maine Cooperative Extension’s Tick Lab. “We don’t have a lot of snow, but what we do have is providing added insulation to the ticks where they are over-wintering. They have adapted quite well to these conditions.”


Researchers say a milder climate caused by global warming may be contributing to the expansion of the deer tick’s range, leading to increased Lyme cases, a bacterial infection transmitted by tick bites. Maine set a record for Lyme disease cases in 2022 with 2,619 cases reported.

So, if a temperature of 18 below zero doesn’t kill them, what would it take to substantially reduce tick populations in Maine?

Dill said that’s uncertain, but based on observations of ticks in lab settings, it would likely take at least two straight weeks of extreme cold, perhaps highs in the single digits and lows of zero degrees Fahrenheit or colder – with no snow on the ground – to knock back tick populations.

“We just haven’t been seeing that kind of weather,” Dill said.

In fact, the relatively warmer winter weather in December and January could even lead to increased tick populations this spring. Dill said that’s hard to predict at this point for a number of reasons, including that we don’t know what the rest of the winter will be like. The tick lab monitors tick populations throughout the state, conducts research and assists the public, among other tasks.

“Ticks can survive in an impressive number of conditions, such as being submerged in water for an extended period of time, or in a drought,” Dill said. “They are a hardy organism that is well adapted to persist across our landscape.”

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