Question

Which is worse for a runner - heat or humidity?

It Is The Heat—And The Humidity

This question about summer weather's impact on a runner has interested me for some time:

A runner runs 5 miles at 6 a.m. one day with cloudy skies, an 80-degree temperature and 80 percent humidity. That same runner a few days later runs 5 miles at 4 p.m. under sunny skies with a 95-degree temperature and 50 percent humidity. Which of the two external weather conditions is more taxing on the runner assuming the exact same running route and running pace? Why?

Paul Scelsi
Dallas, TX