I was thinking about running in this heat recently, and wanted to ask: Which extreme would you rather run in, the heat or the cold? I would roughly estimate that the 90's is like the teens in the Winter, 100 is like zero or single digits, 80's is like 20's, 70's is like 30's, etc...
Anyway, I think I'd still take an extreme hot run over the extreme cold run. Both are very uncomfortable and in both it limits what you can do. I've felt heat exhaustion and frostbite both, neither are pleasant. I guess what tips the scales is you are bundled up with tons of clothes in the cold, and that's a pain. It is awfully nice in warm weather to only have to worry about shorts, socks, and shoes.
Winter running in general also has other factors that make it a pain. Poor footing much of the time, running in the dark a lot because of short daylight, and the wind matters a lot more. Also, in heat, at least you have a bigger variety of routes to choose from, whereas in winter, lots of paths/trails/sidewalks become unrunnable and your options become limited.