Cold Weather Doesn't Directly Cause Illness

The belief that cold weather directly causes illness is a persistent myth. Viruses and bacteria cause illness, not temperature changes. You cannot 'catch a cold' from being cold, wet, or going outside with wet hair. However, cold weather can indirectly increase illness rates in several ways: people spend more time indoors in close proximity, increasing virus transmission; cold air may dry nasal passages, reducing their effectiveness as a barrier; and some research suggests cold stress might temporarily weaken immune function. Additionally, many respiratory viruses survive longer in cold, dry conditions. The correlation between cold seasons and increased illness led to the misconception that cold itself causes sickness. Controlled studies have shown that people exposed to cold temperatures are no more likely to develop infections than those kept warm, unless they're also exposed to pathogens.