Despite growing up in the hot Las Vegas desert, I actually don’t like hot weather. To this day I still struggle a lot in warm temperatures. This might have something to do with why I acclimate so well to cooler wet climates like Seattle and the extremely cold winters of Chicago.
I work hard year round to acclimate to rising or falling temperatures. Spring and summer not only are no exception but in my case it’s crucial to handling runs in summer heat. My forehead for some reason won’t sweat for some time when it warms up (it eventually will by mid/late summer) and that exacerbates how hot conditions feel for me.
Also, with a bigger frame than other runners, I absorb and retain heat a lot better than others. That’s great in winter, and not so great in summer.
I have a hard time with basic runs when it gets hotter than before. 65-70 degrees will probably feel okay in September, but right now it’s like a sauna of death for me to run in. I have a hard time going more than a couple miles without stopping, and in suitably hot conditions I may even have to stop for good after a couple miles.
If regular runs are hard, you can imagine what speedwork and races feel like. Speedwork at least usually allows you to stop and rest every few minutes. A race, however, demands a non-stop effort until you reach the finish line. Even a 5K may be too much if it’s warm enough.
Now consider the challenge of running a full marathon. By itself in ideal conditions it’s a monumentally difficult feat. Add in any warmth above 60 degrees and you’ve exponentially increased the difficulty. Once temperatures reach an otherwise mild 70 degrees you actually begin to put runners’ health in danger.