^^^Even the humidity comes into play as the higher it is, in hot or cold weather, the more miserable you will be.
Heat is bad but at least you can physically play. Cold sucks the life out of your horn and makes intonation go crazy.
You're so right about playing in high temps. In high school I passed out during a marching band parade in Kansas- over 100 degrees and I was wearing a full polyester uniform with a "Q-tip" hat, plastic chest overlay and gloves, playing saxophone for several blocks. They said the formation came to a stop and I just spinned around twice and tumbled to the ground.I did an outdoor solo gig for two hours a couple of weeks ago. It was 45 degrees and uncomfortable. The next day it was 55 and didn't feel nearly as bad. 55 is probably my cut off point for a daytime gig.
I've played in the extreme heat a few times. The worst was years ago in Maracaibo Venezuela. I sweat through my clothes and when we finished I had stopped sweating, that's when the heatstroke was starting to set in. It took me a few hours to drink enough water to feel right again.
I'll still take the heat over the cold.