I have a touch of Raynaud's, but with the wind chill it affects me much more on the bike than it does running. I'll wear shoe covers up to nearly 70°F ... and short sleeves with no arm warmers at 60°? Forget about it. My main issue with the cold and running is motivation. As I've said before, when I'm already freezing, it's a huge act of will to take off whatever I'm wearing (usually two or three layers of wool!) and put on freezing cold running gear.

If I'm acclimated I don't mind heat. But it definitely slows me down. And in the last couple of years, temperatures have been so variable that it hasn't been possible to acclimate to heat.