A WBGT reading at the field
- Taken at the practice surface, in the sun, about 15 minutes before practice.
- Repeated every 30 minutes and written down with the time.
High school football has the highest heat illness rate of any American high school sport, and the preseason is where nearly all of it happens. The combination is specific: August heat, athletes with no acclimatization after a summer indoors, equipment that blocks evaporation, and programs that vary enormously in how seriously they take the first week.
The variation is the problem. The science is settled and the protocols are published. What differs between a program where nothing happens and one where someone collapses is whether the protocols are actually followed when it is inconvenient.
Days 1-5When most preseason heat illness occurs
Under 10 minTarget from collapse to cold-water immersion
+6°FWhat full pads add to effective WBGT
Every 30 minHow often readings should be taken and logged
What the state rules require
Heat policy for high school athletics is set by each state's athletic association, not nationally, so the specifics vary. The direction of travel is consistent: more states are moving from heat index to WBGT, and from recommendation to requirement.
Texas is the clearest recent example. The UIL WBGT policy became mandatory on August 1, 2026 for outdoor athletic practice and marching band, with required readings before and during practice, required logging, required practice modifications by threshold, and a cold-water cooling zone from 80°F WBGT upward. Thresholds vary by region of the state.
Check your own association's current policy rather than assuming. Several states have changed theirs in the last few seasons, and a coach working from a memory of the old rules is a common failure mode.
The acclimatization period is the dangerous part
Most exertional heat illness in athletics happens in the first three to five days of preseason, not on the hottest day of the year. A heat acclimatization period exists to spread that load, and it is the single highest-value thing a program does.
- Days 1 to 2: one practice per day, maximum three hours, helmets only for football, no contact.
- Days 3 to 5: one practice per day, maximum three hours, helmets and shoulder pads, contact limited to blocking sleds and dummies.
- Days 6 onward: full equipment permitted, and double practice days may begin.
- On a double practice day, the two sessions are separated by at least three continuous hours of rest, and a double day is never followed by another double day.
- Walk-throughs do not count as practice, as long as no conditioning or equipment is involved and they stay separated from practice by three hours.
These are the widely adopted NATA-derived guidelines. Your state association's version governs; most are close to this.
What should be on the field
None of this is expensive. All of it is the difference between a scare and a death.
Cold-water immersion, ready
- A stock tank or tub, water and ice, filled before practice from roughly 80°F WBGT.
- Cool first, transport second. Rapid cooling is what makes heat stroke survivable.
Unrestricted water
- Available at all times, not only at scheduled breaks.
- Never withheld as discipline or as conditioning. This has killed athletes.
Someone with authority to stop
- Usually the athletic trainer. The role must be able to modify or end practice without negotiating with a coach.
- Named in the written policy, not assumed.
Questions parents should ask
Any program doing this well will answer these immediately and without irritation. Hesitation is itself the answer.
- Do you measure WBGT at the practice field, and how often?
- Who takes the reading, and who has authority to modify or stop practice?
- Is a cold-water immersion tub on the field during August practices, filled, before anyone needs it?
- Is there a certified athletic trainer present at practices, not only at games?
- What is the heat acclimatization schedule for the first five days, and does it include equipment limits?
- Is water available at all times, or only at scheduled breaks?
- What is the written emergency action plan for heat illness, and has the staff rehearsed it this season?
What players should know
- Symptoms are information, not weakness. Dizziness, nausea, chills in the heat, a bad headache or confusion all mean stop and say something now.
- Watch your teammates. The athlete in trouble is often the last to recognize it, and confusion is an early sign.
- Arrive hydrated. You cannot catch up during practice, and the night before matters more than the hour before.
- If you were sick this week, had a fever, or slept badly, tell the trainer. The margin is smaller than usual.
- Helmets off during every break. It is part of the cooling, not a formality.
Warning signs of heat illness
Heat stress shows up before it becomes an emergency. Anyone on site should speak up immediately on any of these:
Dizziness or lightheadedness
Nausea or vomiting
Chills or goosebumps in the heat
Severe or throbbing headache
Confusion or out-of-character behavior
Stumbling, cramping or collapse
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.
Check the number yourself
Parents do not have to take anyone's word for the conditions. The free app shows real-time WBGT for your town and forecasts it hour by hour, so you can see the same kind of number the program should be using.
- 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
What temperature is too hot for high school football practice?
Measured as WBGT, most state guidelines cancel outdoor practice above 92°F and require helmets and shoulder pads only with a two hour cap from 87°F. Air temperature alone is not a usable threshold because humidity, sun and wind change the risk enormously.
Do all states require WBGT for high school football?
Not yet, but the number is growing. Some states require it, some permit heat index as an alternative, and some leave it to districts. Texas made WBGT mandatory for outdoor practice and marching band from August 1, 2026 through the UIL.
When is high school football heat risk highest?
The first three to five days of preseason practice, when athletes are unacclimatized. This is why the heat acclimatization period limits practice length, equipment and double sessions during that window.
What should a school have on the field for heat emergencies?
A cold-water immersion tub filled before practice, unrestricted water, a WBGT reading taken at the field, a written emergency action plan, and ideally a certified athletic trainer present at practices rather than only at games.
Can parents check WBGT themselves?
Yes. The free WBGT app shows real-time and forecast WBGT for any city, so you can see the conditions for yourself and ask informed questions about how practice is being run.
Related WBGT guides
Know the real heat number
Real-time WBGT, flag levels and forecasts. Free on iPhone.
