Despite the name you don’t get sick from cold weather but from viruses that make you sick. During cold season we stay indoors more which increases our likelihood of being exposed to other people that are sick.
During the Cold War, with the possibility of fighting in the USSR, the US Army conducted experiments with soldiers doing extended bivouacs outside in cold weather to see whether there was increased likelihood of sickness. They couldn't find any evidence that it did.
I mention this as the grandparent comment talks about friends in teaching.
> During cold season we stay indoors more which increases our likelihood of being exposed to other people that are sick.
For most people this is not really true nowdays. We work in the same offices and use the same kind of transport when going to the office. We shop in the same stores.
The seasonal lifestyle change is fairly miniscule.
Did you mean not _just_ contact with people? Many folks who isolated during covid saw a reduction in illnesses regardless of season.
So there's at least 4 mechanisms:
- warmer = less likely to catch a cold
- more time outside = more UV which kills pathogens
- more time outside = less time spent exchanging pathogens with other people
- more time outside = more infrared radiation which boosts the immune system