Florida is classified as a Class 3 zone state for athletic heat stress, one of the highest wet bulb globe temperature risk categories in the country. Since the Zachary Martin Act, every FHSAA member school has been required to monitor heat stress, modify activity based on WBGT, and keep cooling equipment on site at every outdoor practice and contest.
We brought together Dr. Douglas Casa of the Korey Stringer Institute, Dr. Dave Martin of Perry Weather, and Jessica Kenning, Head Athletic Trainer at The First Academy in Orlando, to walk through what the policy actually asks of schools. Here is what they covered.
The History of Heat Illness in High School Athletics
Between 1980 and 2009, there were 159 fatalities among youth, high school, and collegiate players. In a sub-sample of 61 exertional heat stroke deaths, the pattern is almost uniform. All 61 occurred during conditioning drills. Ninety-seven percent of the victims were linemen. Thirty-seven percent were being punished with exercise at the time.
Dr. Casa has been tracking that concentration for three decades.
“From 1995 till now, if the position was known for a high school football player, every single heatstroke death in high school football has been a lineman. And we’ve known this for a long period of time. We’ve also known physiologically that they heat up faster and cool down slower, their sweat rates are higher.”
– Dr. Douglas Casa, CEO, Korey Stringer Institute
Football is not the only exposure. Distance running carries comparable risk, and Dr. Martin has seen more than 40 finishers at a single Falmouth Road Race come in at an internal body temp above 104 degrees.
What Georgia Proved About WBGT Policy
After a 2005 heat stroke death, Georgia’s legislature required every high school to have a heat policy but let each school set its own threshold. That went about as well as you would expect.
“Some high schools were very sarcastic and set their threshold at 150 degrees heat index. He knew that wouldn’t work.”
– Dr. Douglas Casa, on then-GHSA Executive Director Ralph Swearngin
Swearngin had athletic trainers across the state log every heat illness alongside the WBGT reading. After two more heat stroke deaths in 2011, he used that data to build a single statewide chart with mandated work to rest ratios, then kept collecting for three more years so the change could be measured before and after.
In the 87 to 89.9 degree band, one of the most common conditions for summer training in the Southeast, heat syncope and heat exhaustion rates fell by roughly 80 percent. In the highest band studied, they fell to zero.
What is Wet Bulb Globe Temperature?
The three measurements schools encounter are not variations on each other. They count different things.
| Measurement | What it accounts for | Why it falls short for athletics |
|---|---|---|
|
Ambient temperature
|
Air temperature only. | Ignores humidity, sun, and wind. Two days at the same reading can carry very different risk. |
|
Heat index
|
Air temperature and humidity. | Built for a person walking in the shade in long clothing. Ignores solar load and wind, and athletes are not in the shade. |
|
Wet bulb globe temperature
Athletics standard
|
Air temperature, humidity, wind speed, and solar radiation. | It doesn’t. Measured on site, where the athletes actually are, which is why it’s the standard used by the military, OSHA guidance, and FHSAA. |
Heat index gets closer than a thermometer, but it was never built for athletes.
“It was created with someone who was walking in the shade, with long clothing on, so it doesn’t have anything to do with the ability for someone to evaporate moisture off of their skin, and use evaporative heat loss to cool themselves off during some type of exercise. Again, the person’s walking, so it’s not applicable to someone who’s exercising.”
– Dr. Dave Martin, Director of Science, Perry Weather
WBGT adds wind and direct solar radiation, which is why it reflects whether an athlete can actually shed heat through sweat. It is also not new. It came out of the US military in the 1940s and 50s, after roughly 600 heat illness cases at Parris Island in the summer of 1952 and six recruit deaths there between 1951 and 1953. The flag system built on WBGT drove those numbers down and has been in use ever since.
Why Your WBGT Reading Looks Lower Than the Temperature
This is the most common point of confusion, and it is worth settling before your coaches ever see the chart. WBGT sits on its own scale. Doing research at White Sands Missile Range, Martin recorded 106 degree ambient temperature at under 30 percent humidity while WBGT never crossed 90. A coach who hears “no activity above 92” and pictures air temperature will assume the season is cancelled.
Kenning got exactly that reaction when Florida adopted the policy.
“We had a coach come in from Arkansas, and that was one of the big questions, was when can we ever practice with all these restrictions? And they actually ended up going in the mornings, because it was cooler, but I had to even remind them then that that doesn’t mean you can stop watching Wet Bulb Globe Temp, because the other day, I was out there at 7am, and we were already at 82 wet bulb, so we were technically in restrictions, and by the end of practice, it was already 84.”
– Jessica Kenning, Head Athletic Trainer, The First Academy
The Four Tenets of Preventing Heat Stroke
Prevention comes down to five levers: heat acclimatization, proper hydration, appropriate work to rest ratios, environmental monitoring, and modifying activity. Nearly all heat stroke deaths happen in the first week of training, which is where acclimatization earns its keep.
If heat stroke does present, survival depends on four things happening fast. Recognize it, and central nervous system dysfunction is the signal: confusion, irrational behavior, collapse.
Confirm it with a rectal temperature, which is the accepted field method and also rules out head injury or hyponatremia. Cool aggressively with cold water immersion. Then finish that cooling on site before transport, the same way you would never wait for the hospital to start chest compressions.
Survivability is 100 percent when core temperature gets under 104 degrees within 30 minutes. Athletes typically present around 108 or 109, which is why the thermometer is not optional equipment. Casa’s direct ask to administrators on the call was to fund rectal thermometers for their athletic trainers and make sure staff are cleared to use them.
The reason the number matters more than how the athlete looks:
“I was caring for a heat stroke victim a couple years ago. He started at 112.8. He was completely incoherent at 112.8, was saying things that made no sense, and screaming, and being obviously irrational, but at 107, he was answering all questions and acting totally normally. If people use subjective responses for the cessation of cooling, people would take him out at 107, and he would have still died from the heat stroke, because he still would have too many minutes above the threshold for cell damage.”
– Dr. Douglas Casa, CEO, Korey Stringer Institute
Recognition is rarely clean in the field. Kenning treated an athlete for rhabdomyolysis whose only symptom was vomiting twice, with normal participation right up to the end of practice. Her working rule is not to see a zebra every time there is a horse, but to stay aware that it could be one.
The FHSAA WBGT Zones
Florida uses a single statewide chart. No regional variation.
Kenning says green flag days are rare at her school, and most Florida practices sit in the 82.1 to 87.0 band. The working assumption should be that rest breaks are on. Her other point is that the chart is written for administrators, not coaches, so she translates each band into what it means for football, cross country, track, and softball specifically before the season starts.
Measurement Requirements
Measurement is required any time the WBGT reading is reasonably expected to exceed 82.0°F. In Florida, that is most of the season.
15 to 20 minutes before Set up the on-site WBGT instrument so it has time to acclimate to conditions.
Every 30 minutes during Re-read throughout the practice, workout, or event.
Whenever you cross into a new zone Adjust activity immediately, whether the reading is rising or falling.
Hydration, Rest, and Cooling Zones
Hydration and Rest. Athletes have unrestricted access to water at all times. An athlete is never denied water. A rest break means unlimited hydration and full rest with no activity involved, taken in a shaded area, with shade tents recommended where natural shade is limited. Electrolytes should be provided on extended-duration or multiple-activity days.
Cooling Zones. Above 82.1°F, cooling zones must be available: cold water immersion tubs or ice and water tarps using the TACO method. A person trained to administer cold water immersion must be present at the cooling zone location.
Emergency Action Plan. Having a plan is not the same as being able to run it. Casa’s guidance is to rehearse three scenarios: the athletic trainer is not there at all, the athletic trainer arrives three or four minutes late, and the athletic trainer is present but needs coaches to assist. Very few athletic trainers can lift a 300 pound athlete into a tub alone, so four or five coaches need to have practiced that lift.
What happens when they haven’t:
“I just testified in a trial of a high school heat stroke case just two weeks ago. And unfortunately, cold water immersion was not used for the football player, because he was too big for them to move the lineman to the cold water immersion tub that they had only 100 meters away. And they didn’t use it because they said it was too big, but they had never rehearsed it. They didn’t have a strategy of putting a person on a tarp to lift onto the gator, or on a slide board onto the gator to get to the tub, and they ended up leaving him in place till the ambulance arrived.”
– Dr. Douglas Casa, CEO, Korey Stringer Institute
The tub was there. Nobody had practiced getting an athlete into it.
Do the Rules Change for Games?
Yes, and this is where schools most often get caught out.
Practices Activity limits apply. The tiered guidelines are mandatory, from normal activity below 82.0°F up to zero outdoor activity at or above 92.1°F. Monitor approximately every 30 minutes throughout the entire session and modify immediately when the reading crosses a tier.
Competitions Activity limits do not apply. Instead, sport-specific mandatory hydration breaks activate above 82.1°F. Officials must honor a request from a school principal or designee to delay, suspend, or postpone for oppressive heat, with the exception of FHSAA State Championship events. Member schools must plan start-time, venue, and staffing modifications in advance of any contest.
Both Above 82.0°F, cold water immersion or ice and water TACO cooling zones must be available.
How Perry Weather Helps Florida Schools
The policy assumes someone is taking a reading every 30 minutes and telling everyone on campus what changed. Usually that person is a single athletic trainer who is also covering a full football practice. Before Perry Weather, Kenning was carrying a handheld out to the field herself and chasing coaches for schedules that were rarely current.
A Perry Weather station measures WBGT on site with a black bulb sensor capturing every five minutes and reporting a rolling average. FHSAA zones are configured in the software, so crossing a threshold sends the specific practice modification, not just a number, to every coach who needs it. A coach new to Florida gets told what to do rather than being handed a chart, and the responsibility stops sitting with whoever happens to be free to walk outside.
At The First Academy, that reach goes past the athletic department.
“My biggest push with my school was to make sure everybody had access to this, so it’s not just one person alerting and having to track every schedule. Because we’re a K-12 school, all of our lower school teachers and admin are also on our Perry Weather, so they know when they can’t send the littles out to the playground.”
– Jessica Kenning, Head Athletic Trainer, The First Academy
Perry Weather also staffs on-call meteorologists 24/7 for schools planning around a specific practice or contest.
If you want to see what automated WBGT monitoring looks like on your fields, get a quote today.
