I have just got back from 2 weeks vacation in the South of France (around the Pyrenees) and got the chance to do some riding over there with the some locals. On the day we road into the Pyrenees and rode the Col d'Aubisque (see Stage 16 of this years TDF) it was 45 C when we left Laruns at the foot of the climb (this is about 113 F). Luckily the temperature dropped over the 19 KMs to the top as it was too hot at the bottom, espeically when the average grade is just a touch over 7% with several signficant sections of 10 - 13 % ( you have got to love the signs that the Frence post each kilometer telling what the average gradient is for the next 1 km coming). Needless the say I was happy to get to the top not to mention very happy to have climbed in 1 hr and 15 minutes!
So for me 113 is probably too hot, although with the right motivation and enough water or water stops, you can suffer through it!