I rode 52 miles in 100F heat, including climbing up 2 7 percent grades at the midpoint. NOT smart. I think I rode the last 15 miles in the early stages of heat stroke - rapid breathing and heartbeat, but I made it home. I'm OK, it was just a little scary (and stupid on my part). I won't start a ride any later than 8:00 in the morning if its going to be 100 like it was (I started riding at almost 11:00).
On the plus side, just broke 2,000 miles cycling for the year
Man, the water at Folsom Lake is LOW!