Reduce Your Warmup
If warm temperatures prevail before your race, do as little as possible before you get to the starting line, including a very limited warmup session. At that point, it’s really more about just activating your muscles, so you don’t necessarily need to run at all. Typically, I have runners do some easy sports band stretching just to remind their muscles that they’re getting ready to move. If you let the race warm you up, you can ease into your race paces. You should minimize the amount of time you’re out in the heat and in the sun prior to the start of the race.