This outbreak has made me realise how I've gone my whole adult life without knowing some basic things about bacteria and viruses. Like, I never knew about how soap dissolves the virus's outer coating...

Anyway apparently hot and wet is good for bacteria, but cold is better for viruses. The bit that made it click for me is that viruses aren't metabolising anything outside of the host-cell, so the best a virus can hope for is to not be destroyed -- and cold is a better preservative.

I'm still not sure whether hot and humid is better than hot and dry though? I think I read that hot and dry is worse, because it increases evaporation.