system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why Do Cold Or Rainy Conditions Promote Sickness?

When I was a kid, all of my friends and I used to love playing outside when it was raining but all of our parents wouldn’t want us to stay out for too long because they all believed that we’d catch a cold or get sick.

I specifically recall one day there was a huge amount of rain for a sustained time and we had a creek behind our cul de sac that basically turned into a small running river. Our parents all said we shouldn’t go outside but we all went to the creek and just floated down it over and over again. Over the next few days all of us got colds. 

Is this a commonly spread myth or is there any scientific basis behind this belief?
gpt
People tend to stay inside more often when it’s cold.  When people group together inside there is a higher chance of spreading the virus to more people, hence why more people get sick in the winter. 

It’s not so much the cold weather that makes us sick but how we shelter from it that increases the spread.