Flu cases are climbing across New York as winter settles in.
But why do cases jump once temperatures drop? Cold weather itself doesn’t directly give you a cold or the flu, but it can weaken the immune system, dry out the respiratory tract and create conditions that help viruses thrive.
“That’s actually not an old wives’ tale,” Dr. Winston Rajendram, a family medicine physician at Northwestern Medicine in the Chicago suburbs, told USA TODAY last winter.
“We find in colder temperatures, the viruses are more active. And then there’s a higher risk of catching the virus during colder temperatures,” he added.
Flu cases on the rise in New York
Flu activity in New York is rising sharply as winter settles in, and state health officials are urging residents to stay home when sick and get vaccinated if they haven’t yet.
The 2025–26 season got off to a slow start: the first week, ending Oct. 4, reported 481 new cases. By Nov. 29, weekly cases had jumped to 14,506, bringing the season-to-date total to more than 32,000 cases, according to data from the New York State Department of Health.
For comparison, the week ending Nov. 30 last year saw 2,900 new cases, with a total of 10,902 cases reported from October through November — about a third of this year’s total — suggesting the 2025 season could be particularly intense for flu and other respiratory viruses.
How many cases have been reported in the Southern Tier?
Here are the positive flu cases in the region for the week ending Nov. 29, the latest available results released by the Department of Health:
Can cold weather make you sick?
Winter is here, and with it comes a parade of sniffles, coughs and fevers — and it’s not just a myth that going barefoot outdoors can put you on the sick list.
Cold temperatures don’t directly hand you the flu, a cold, RSV or other viral infections, but they roll out a roster of conditions that make it easier for viruses to spread and can nudge your immune system off balance, according to a 2015 study from Yale University.
“The body is generally good at responding to drops in temperature,” Andrew Pekosz, a professor of molecular biology and immunology at Johns Hopkins Bloomberg School of Public Health, told USA TODAY last year, “but the nose and upper respiratory tracts can respond more slowly.”
And while our defenses may weaken in cold weather, viruses can get tougher. The National Institutes of Health notes that the flu virus spreads more efficiently at lower temperatures because its lipid coating stiffens, increasing the odds of exposure.
Then, when people sick with a virus do sneeze or cough, they release respiratory droplets containing the virus, Pekosz said last year. In cooler, drier air, those droplets hang around longer, raising the chances of infecting people nearby — the same effect can happen with air conditioning, which also reduces humidity.
“That opens up a wider window of time that you could potentially get infected if you walk into a room, or if you touch a surface that someone has just contaminated with these viruses,” Pekosz said.
Viruses fare much worse in warmer, more humid conditions. Research suggests flu viruses in humid air can cling to water molecules and fall out of the air, preventing them from lingering and infecting others.
And yes, cold feet can make a difference. A 2005 study at the Common Cold Centre in Cardiff, England, found that students who dunked their feet in cold water for 20 minutes were more likely to develop a cold over the next five days. Chilly toes constrict blood vessels in the nose, slowing immune defenses — so those slippers aren’t just cozy; they can be your first line of defense.
But ironically, it’s not just the bitter cold outdoors you have to watch — the crowded warmth indoors plays a big role too. Winter weather drives people inside, where germs linger on doorknobs, keyboards and shared surfaces. Add holiday travel and packed parties to the lineup, and superspreader events happen just like that.
Of course, cold weather can also cause noncontagious illnesses, like hypothermia or frostbite. These aren’t passed from person to person, but they are a direct result of cold exposure — the very situations where bare feet or wet hair could become dangerous.
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Contributing: Eduardo Cuevas, USA TODAY
Brandi D. Addison covers weather across the United States as the Weather Connect Reporter for the USA TODAY Network. She can be reached at baddison@gannett.com. Find her on Facebook here.
This article originally appeared on The Evening Tribune: Can cold weather make you sick? Flu cases rising in Steuben County, across NY
Reporting by Brandi D. Addison, USA TODAY Network / The Evening Tribune
USA TODAY Network via Reuters Connect
