How do coaches decide whether to change or cancel practice because of heat?

Q: How do coaches decide whether to change or cancel practice because of heat?

NFHS guidance (October 2025) says to follow a heat safety table to decide whether to start, modify or stop practices and games. Wet Bulb Globe Temperature (WBGT) measured on site is the "gold standard" for heat stress. Take the reading 10 to 15 minutes before practice or a game and compare it with a heat safety table, such as the National Athletic Trainers' Association (NATA) WBGT guidelines. No WBGT device? Use the heat index for your location instead. Humidity matters, not just temperature. 95°F with 40% relative humidity carries a likely risk of heavy sweat loss and heat illness during strenuous activity. The risk at just 85°F with 70% or higher humidity is likely the same or greater. Watch for irrigation. Sprinklers run before early-morning practice can raise humidity on the field even in dry climates. As conditions get hotter or more humid, coaches should lower intensity, give more frequent and longer rest breaks, consider reducing uniform and equipment, and watch athletes more closely, especially when the weather has changed from the previous few days. State rules can differ. Your state athletic association may set its own heat guidelines for your region, and NFHS recommends following state or regional guidelines strictly.

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Accepted Answer

NFHS guidance (October 2025) says to follow a heat safety table to decide whether to start, modify or stop practices and games.

Wet Bulb Globe Temperature (WBGT) measured on site is the "gold standard" for heat stress. Take the reading 10 to 15 minutes before practice or a game and compare it with a heat safety table, such as the National Athletic Trainers' Association (NATA) WBGT guidelines.
No WBGT device? Use the heat index for your location instead.
Humidity matters, not just temperature. 95°F with 40% relative humidity carries a likely risk of heavy sweat loss and heat illness during strenuous activity. The risk at just 85°F with 70% or higher humidity is likely the same or greater.
Watch for irrigation. Sprinklers run before early-morning practice can raise humidity on the field even in dry climates.

As conditions get hotter or more humid, coaches should lower intensity, give more frequent and longer rest breaks, consider reducing uniform and equipment, and watch athletes more closely, especially when the weather has changed from the previous few days.

State rules can differ. Your state athletic association may set its own heat guidelines for your region, and NFHS recommends following state or regional guidelines strictly.