Does cold weather really cause colds? Science explains why winter sniffles spike

Medical experts say chilly weather does not directly cause colds, despite a common belief.

Cold and flu cases rise in winter mainly due to indoor behaviour, not outdoor temperatures.

Understanding the real cause helps people focus on effective prevention, not myths.

Children, office-goers, commuters, and families are most affected during colder months.

Many people blame cold weather for coughs and runny noses, but medical science tells a different story. Going outside in chilly conditions does not make you catch a cold. Instead, experts say the seasonal rise in infections is driven by how people behave during winter, not by exposure to low temperatures.

What actually causes a cold

The common cold is triggered by viruses, not by cold air. According to John Tregoning, Professor of Vaccine Immunology at Imperial College London, winter infections increase due to correlation, not causation.

In simple terms, cold weather coincides with higher infection rates, but it is not the direct cause.

Why winter sees more infections

Doctors and epidemiologists point to behavioural changes during colder months as the main driver.

People spend more time indoors, often in close proximity.

Ventilation is poorer, with windows closed to keep warm.

Viruses spread more easily in enclosed spaces through coughing, sneezing, and talking.

This combination creates ideal conditions for respiratory viruses to move quickly from person to person.

Does sunlight make a difference?

Yes, but only marginally.

Researchers note that UV light from the sun can deactivate viruses. In warmer months, viral droplets released outdoors are more likely to be exposed to sunlight and dry air, which can reduce their survival.

In winter, reduced sunlight and slower evaporation may allow viruses to persist slightly longer. However, experts stress that this effect is secondary to indoor crowding.