I wish I were having the 90 degree problem... I got back into cycling during the unusually warm winters of 2011 and 2012, and the actual winter we had in the Ozarks this past year threw off my training to the degree that I over-did it when ride-able weather finally returned.
I will ride into the upper-90's, but take great care with hydration and resting. My first metric century was attempted during a humid Ozarks August with temp in the 90's, and I damn near didn't make it home when I ran out of fluids and it felt like my limbs were falling apart at the joints. A cool park museum and water fountain 3 miles from my house saved me from having to make the call-of-shame, and I learned that lesson very well.
I am definitely becoming a warm-weather fan as I get more into cycling - it feels better, and the added bonus of fewer clothes to launder is appreciated.