Hot run today

This morning did no run predawn, woke very early yesterday and went very late for a nap, so I slept in a bit. At 11 a.m. went out for my run, went out to the conservatory, 6 laps there and came home, felt strong and good, but in the last lap felt a bit thristy and tired, dont know if that is mentally, finished the 8.5k run in 48:40. Ran with the watch on time of day though. The weather was ridiculous hot today, I am going to opt for a predawn run tomorrow. It seems that my body is used to the 9:10 or so pace per mile even without looking at the watch, How do I get that pace to 7:30 range for easy days at the same effort as a lot of guys here train at that pace or faster, I would like to be there! Happy humpday!