I found a surprising statistic about running in the heat. Runnersworld.com comments that you should slow your pace down in the summer months or excessive heat.
“Slow down: Every 5°F rise in temperature above 60°F can slow your pace by as much as 20 to 30 seconds per mile. So don’t fight it—just slow down.”
I thought it was just my problem with heat running but it’s good to know that there’s a reason behind it.