The idea that you can catch cold from cold air is a long-perpetuated myth. But it's now turned out to be true, sort of. No, you can't actually catch a cold from the cold but it does hamper the nose's immune response to airborne viruses and bacteria, from cold to the flu and COVID-19. From CNN:
In fact, reducing the temperature inside the nose by as little as 9 degrees Fahrenheit (5 degrees Celsius) kills nearly 50% of the billions of virus and bacteria-fighting cells in the nostrils, according to the study published Tuesday in The Journal of Allergy and Clinical Immunology.
"Cold air is associated with increased viral infection because you've essentially lost half of your immunity just by that small drop in temperature," said rhinologist Dr. Benjamin Bleier, director of otolaryngology at Massachusetts Eye and Ear and an associate professor at Harvard Medical School in Boston.
The best defense, according to the researchers? Wear a mask.
"Not only do masks protect you from the direct inhalation of viruses, but it's also like wearing a sweater on your nose," Bleier says.