It's Not the Heat, Nor the Humidity....It's the dew point.
|DEW POINT (°F)||RUNNER'S PERCEPTION||HOW TO HANDLE|
|50–54 (10-12C)||Very comfortable||PR conditions|
|55–59 (13-15C)||Comfortable||Hard efforts likely not affected|
|60–64 (16-18C)||Uncomfortable for some people||Expect race times to be slower than in optimal conditions|
|65–69 (18-20C)||Uncomfortable for most people||Easy training runs might feel OK but difficult to race well or do hard efforts|
|70–74 (21-23C)||Very humid and uncomfortable||Expect pace to suffer greatly|
|75 or greater (24+C)||Extremely oppressive||Skip it or dramatically alter goal|