Too hot for speedwork here, too. Just much hotter than it's been.
I was dripping with sweat just sitting around the house - and flirting with heat stress on my slow 4.5. I was being careful though and would've quit and walked back home if I needed to.
Oddly my HR never got very high, but yet I was just on the edge of feeling like it was time to quit - didn't quite stop sweating, didn't quite get chills, but it sure felt like it could happen any moment.
Speed comes from what you put behind you. - Judi Ketteler