COVID-19 Resource Center

Review the latest information on visitor policies, safety procedures, vaccines, and more in the COVID-19 Resource Center.


Can Winter Make You Sick?

Cold Temperatures Linked to Illness

The thought of cold weather might make you feel weary, but do falling temperatures play a role in illness? As a matter of fact, they do. Different types of viruses thrive in different conditions. For example, common cold viruses are most active in cooler weather. The coating of the flu virus is actually tougher at near-freezing temperatures, making it harder to combat. But other factors may be at play, too.

Being Cold Can Cause a Cold

Perhaps your parents used to warn you not to go outside in the cold with wet hair. To the chagrin of their parents, students today are often seen walking to school in shorts, without jackets and hats, even in frigid temperatures. While these behaviors can lead to frostbite or hypothermia, can they also make a person more likely to pick up a virus? Some research suggests the answer is yes. Being cold actually may reduce your body’s ability to fight infection, and the cold air in your nasal passages may reduce your immune cells’ ability to fight off the virus in your nasal passage.

Go Outside Anyway

If being cold can make you sick, it might seem like staying inside is your safest choice. It’s not. Not only are you more likely to pick up germs indoors, you’re also limiting your sun exposure, which can cause your vitamin D levels to plunge. Low levels of vitamin D have been linked to influenza A and a weakened immune system, plus a variety of health issues, including fatigue, general achiness and even cancer.

Dangers of Dry Air

Dry winter air is great for the flu virus – and not so great for you. Research shows that dry winter air allows the flu virus to spread. Air inside your home also tends to also be dry in the winter due to heating, and this can dry out your nasal passages, making them less effective at fighting off viruses. Plus, viruses spread more easily through dry air because fewer water molecules are available to interfere with their projection through the air when expelled through a sneeze or cough. One study found that good ventilation combined with high relative humidity indoors rendered the influenza A virus inactive.

If You Can’t Fly South for the Winter

If the snowbird life isn’t in your future, there are still things you can do to keep Jack Frost from getting you sick.

  • Avoid the temptation to hibernate this winter. Try to get outdoors for 10 to 15 minutes every day, and show a little skin — sun-exposed skin makes vitamin D.
  • When you go out, bundle up, and wrap a scarf around your mouth and nose to limit exposure to viruses.
  • Maintain higher humidity levels in your home and office to keep nasal passages healthy and battle airborne transmission of viruses.
  • Keep an eye on your heart health. Deaths from heart attacks, strokes and other cardiovascular conditions tend to spike in the winter, possibly due to increased blood pressure caused by colder temperatures.
  • Consider getting a flu shot, and read about other ways to fight the flu.
  • If you catch the flu bug, get the rapid flu test at one of the Northwestern Medicine Immediate Care Centers, to allow for immediate treatment to begin to reduce the severity of the illness.

Learn more about symptoms of cold versus flu, testing for influenza and why the flu shot doesn’t make you sick.