A football heat calculation has three steps, and skipping the middle one is how a practice that looks compliant on paper turns into a medical emergency on the field.
One: get the WBGT. Two: add the equipment adjustment for what athletes will actually wear. Three: look the adjusted figure up and set practice accordingly.
The three steps
- Get the reading with the WBGT calculator or a device at the field. Measure at the practice surface, in the sun, not in the shade of the field house.
- Add the equipment adjustment: about 6°F for full pads, 4°F for helmet and shoulder pads, 2°F for helmets only.
- Look the adjusted number up in the table below, announce the structure, and set a break timer.
Equipment adjustment
| Equipment | Add | Why |
|---|---|---|
| Shorts, shirt, helmet | about 2°F | The head sheds a disproportionate share of body heat |
| Helmet and shoulder pads | about 4°F | Shoulders, chest and upper back lose evaporative capacity |
| Full pads | about 6°F | Roughly half the body surface is covered and airflow is blocked |
Adjusted WBGT, worked out
The same 86°F afternoon, by what the athlete is wearing.
| Who | Adjusted WBGT | Practice allowed |
|---|---|---|
| Skill player in shorts and a shirt | 86°F | Normal practice, four-minute breaks three times an hour |
| Player in helmet only | 88°F | Two hours maximum, four breaks an hour |
| Player in helmet and shoulder pads | 90°F | One hour maximum, no conditioning, 20 minutes of break |
| Lineman in full pads | 92°F | At the cancellation threshold |
This is the point of the exercise. One reading, one field, one practice, and four genuinely different answers. Set practice by the most exposed group on the field, not the average.
Practice structure by adjusted WBGT
| Adjusted WBGT | Length | Breaks | Equipment |
|---|---|---|---|
| Under 82.0°F | Normal | 3 per hour, 3 min | Full pads |
| 82.0 to 86.9°F | Normal | 3 per hour, 4 min | Full pads, monitor closely |
| 87.0 to 89.9°F | 2 hours | 4 per hour, 4 min | Helmets and shoulder pads |
| 90.0 to 92.0°F | 1 hour, no conditioning | 20 min within the hour | Helmets only |
| Above 92.0°F | Cancel outdoors | — | — |
Adjustments the table does not make for you
Synthetic turf
Turf can run 40 to 60°F above air temperature in full sun and radiates upward. A grass-field reading understates a turf practice.
Acclimatization
In the first five days of preseason, treat thresholds as lower than published. This is when heat illness actually happens.
Time of day
WBGT peaks after air temperature. A late afternoon session can be hotter by this measure than the midday number suggested.
Body mass
Linemen generate more metabolic heat and shed it more slowly. They are the group the practice plan should be built around.
What actually prevents heat illness
The reading tells you the environment is dangerous. These are the things that change the outcome once you know.
Unrestricted fluid access
Water available at all times, not only at scheduled breaks. Withholding water as discipline has killed athletes.
Cold-water immersion on site
A tub, water and ice, ready before practice starts from roughly 80°F WBGT. Cooling first, transport second, is what survives heat stroke.
Breaks that are real
In shade, with helmets off and fluids in hand. A break spent standing in the sun listening to coaching is not a break.
A culture of speaking up
Athletes hide symptoms when toughness is the measure. The program has to make reporting normal and costless.
When in doubt, cool first and call for help. Collapse or confusion in the heat should be treated as possible exertional heat stroke: begin cold-water immersion immediately and call 911. Cooling comes before transport.
The reading, without the first step
The app computes live WBGT for your field and forecasts it hour by hour, so the only work left is the equipment adjustment and the lookup.
- Real-time WBGT for your location or any city
- Hourly and 14-day WBGT forecasts to plan ahead
- Color-coded flag levels with mode-specific guidance
- Humidity, wind, sun and cloud cover behind every reading
WBGT is estimated from weather data with the peer-reviewed Liljegren model. Where a policy requires on-site measurement, use the app for planning and as a cross-check alongside your instrument.
Common questions
How do you calculate heat stress for football practice?
Take a WBGT reading at the practice surface, add the equipment adjustment for what athletes will wear, roughly 6°F for full pads, then look the adjusted value up in your activity guidelines for practice length, break schedule and equipment limits.
What temperature is too hot for football practice?
Air temperature is the wrong measure. Most guidelines cancel outdoor practice above 92°F WBGT, which can occur on an afternoon with an air temperature in the high 80s if humidity is high and wind is light.
Does the heat index work for football?
Poorly. It assumes shade and light wind and ignores the field surface, so it misses most of what makes football practice dangerous. Use WBGT with an equipment adjustment.
Should practice be set by the average athlete or the most exposed?
The most exposed. If linemen are in full pads, the practice plan is governed by their adjusted WBGT, even if skill players in shorts would be fine under the unadjusted reading.
How often should the reading be retaken during practice?
Every 30 minutes, and logged each time. Wind dropping in the late afternoon can move WBGT several degrees within a single session, which is enough to change the equipment rule mid-practice.
Related WBGT guides
Know the real heat number
Real-time WBGT, flag levels and forecasts. Free on iPhone.
