I woke up just before 6 today to run. But I let my daughter's pleas for snuggling keep me in bed and I didn't get outside until 7. OMG. Crotch-hot. I think it was already over 80, since the high for today is 109. I ran my 3mi, but that's the last time. I was dripping when I got home. I sat down, drank a sports drink and was still sweaty. I took a cool shower and once I dried off, beads of sweat were still collecting on my brow. I'd say that's too close to being overheated.
At least it was still early enough for me to see some rabbits and quail on my run.
Of all the reasons for a pregnant woman to stop running, I really didn't think the heat would do me in. But glancing at the forecast, it appears the days with lows below 80 are swiftly ending. I'll keep getting out there in the morning until they do.