Does Cold Weather Cause the Common Cold?

A common cold is a collection of symptoms affecting the upper respiratory tract—primarily the nose, throat, sinuses, and larynx (voice box). It’s caused by a variety of respiratory viruses, most notably rhinoviruses, but also adenoviruses, coronaviruses, and others.

These viruses spread mainly through airborne droplets from coughing, sneezing, or talking, especially in close contact settings. They also survive on surfaces, where they can be picked up by touch and transferred to the mouth, nose, or eyes.

A well-known belief, especially among concerned grandmothers, is that being exposed to cold weather causes you to catch a cold.

But is there truth to that, or is it just a myth?

Strictly speaking, cold weather itself does not cause the common cold. The viruses that cause it need a human host. However, the incidence of colds does spike during colder months, and this seasonal pattern isn’t just a coincidence.

Here are three key reasons why cold weather is closely associated with catching a cold:

1. Start of the School Season

Fall and winter bring the beginning of the school year, and schools and kindergartens are breeding grounds for viruses. Children are especially susceptible to colds because their immune systems are still developing, and they’re in close contact with many other kids who may carry different pathogens.

Parents often find that once their child starts school or daycare, someone in the household is always sick. Kids bring home viruses, which then get passed along to adults, making schools a powerful catalyst for community-wide viral spread.

Additionally, young children aren’t exactly known for their hygiene: they often don’t cover their mouths when they sneeze, and their handwashing can be inconsistent. This increases the chance of respiratory viruses spreading rapidly in school settings.

2. Poor Ventilation in Cold Weather

When it’s cold outside, we tend to seal up our homes and workspaces to retain heat, which means less fresh air is circulating. In contrast to warmer months when windows are open and airflow is more consistent, indoor air during winter becomes stale and virus-laden.

Respiratory viruses spread much more efficiently in poorly ventilated, crowded indoor environments. Think of packed classrooms, crowded buses, or even family gatherings with all the windows shut. These conditions are perfect for airborne viruses to linger in the air longer, increasing the chances of transmission.

It’s a modern problem, but also something we share with our ancestors. Even in medieval times, people retreated indoors during the cold season, often with minimal ventilation, leading to spikes in illnesses.

3. Cold Air and the Immune System

While cold weather doesn’t cause the virus, it can make your body more vulnerable to infection.

Here’s how:

• Cold, dry air dries out the mucous membranes in your nose and throat, which normally act as a barrier to pathogens. When this layer is compromised, viruses can enter your body more easily.
• Exposure to cold air can constrict blood vessels in the nose, potentially reducing the number of immune cells available to fight off pathogens at the site of entry.
• Some research has shown that rhinoviruses replicate better at cooler temperatures, such as those found in the nasal passages during winter, further boosting their ability to spread.

Even studies in animal models have found that lower temperatures reduce immune responses in the respiratory tract, suggesting that the cold weakens local immunity just enough to give viruses a foothold.

So, Is It a Myth?

Not exactly.

The idea that simply being cold gives you a cold is technically incorrect. You need exposure to a virus. But cold weather sets up the perfect conditions for viruses to thrive and spread: indoor crowding, reduced ventilation, and a mildly suppressed immune defense.

So next time your grandmother tells you to wear a scarf or close your coat, she might not be wrong after all, not because the cold will infect you directly, but because staying warm and avoiding crowded, poorly ventilated places does reduce your chances of getting sick.

TL;DR:

Cold weather doesn’t directly cause the common cold, but it contributes to conditions that make us more susceptible. The start of the school season brings kids into close contact, poor indoor ventilation spreads germs, and cold, dry air weakens our immune defenses. While the cold itself doesn’t cause illness, it creates the perfect environment for viruses to thrive and spread.