Today's work out for my early marathon training has me running 5 miles at my tempo pace (6 min per mile) how much do I compensate for this when it's 90 degrees out in 61% dew points? I had to slow down considerably to get the workout done. My tempo pace was around 6:30 per mile and that felt like I was nearly pushing it. When I was up north my tempo pace at 6 min per mile felt very comfortable.