What the evidence does not support is the idea that simply being cold, such as stepping outside without a coat, directly causes a cold or flu. Instead, cold weather acts as a risk amplifier. It creates conditions that help viruses survive, spread, and overcome the body’s defences.
Understanding this distinction has practical value. Improving indoor ventilation and maintaining adequate humidity during winter can reduce transmission risk. Supporting immune health, including maintaining adequate vitamin D levels, may also help.
Public health messages are most effective when they focus on how viruses spread through contact and respiratory droplets, rather than reinforcing the myth that cold exposure alone causes illness.
In short, cold weather and illness are linked — but not in the way many people assume. Cold temperatures do not cause infections by themselves. Instead, they shape the biological, environmental, and social conditions that allow respiratory viruses to thrive.
Recognising this complexity helps explain why colds and flu peak in winter and supports more effective strategies for prevention, while dispelling a simple but misleading belief about cold weather and sickness
