We brought together Dr. Kechia Rowles of Rockdale County Public Schools, Jeff Hopp of Marietta City Schools, and Dr. David Martin of Perry Weather to walk through what the GHSA WBGT policy actually requires heading into the most dangerous stretch of the year. Here is what they covered.
The History of Heat Illness in High School Athletics
The first two weeks of school are statistically the most dangerous period of the year for heat-related illness. Kids come off a summer of less structured activity, practices are ramping back up, and bodies haven’t had time to adapt. Dr. Martin opened with the research explaining why.
A 2018 study by Dr. Andrew Grundstein, a University of Georgia meteorologist, looked at heat stroke fatalities in youth, high school, and collegiate football from 1980 through 2009: 159 deaths total. In a sub-sample of 61 of those, 100 percent occurred during conditioning drills, 97 percent of the victims were linemen, and 37 percent were being conditioned as punishment.
Heat stroke is not confined to hot days, either. Dr. Martin relayed an account from an athletic trainer he met at a Korey Stringer Institute conference in Albany:
“The Boston Marathon was fifty degrees ambient temperature, and there were nine heat strokes at the Boston Marathon. I asked him why he thought that was, and he said, well, it was really cold at the start line. People were wearing extra clothes, and they didn’t want to lose their clothes. So they ran with them on and eventually succumbed to heat stroke.”
– Dr. David Martin, Director of Science, Perry Weather
The Georgia Study That Became the National Model
The seminal research behind Georgia’s own policy came from Georgia. Bud Cooper and Dr. Grundstein, both at the University of Georgia, asked a direct question: what happens if schools actually implement activity modifications, removing equipment above certain temperatures, adding rest breaks, capping practice time by WBGT category?
The result, once schools implemented those changes, was a 30 to 100 percent decrease in heat illness across every modification category studied. That research is what set off the broader move toward WBGT-based state policy nationwide, including Texas’s own mandate, which took effect this year.
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. |
Ambient temperature accounts for air temperature only. Heat index adds humidity, but it was built around a person standing still in the shade, fully clothed, not an athlete sweating through a two-hour practice.
WBGT, developed by the military in the 1950s, combines air temperature, humidity, wind speed, and solar radiation into a single number that reflects what an exercising body actually experiences.
Dr. Rowles, who fields these questions from parents and coaches directly, said the confusion almost always starts with a phone screen:
“When we look at the WBGT devices we use, there’s the wind, the humidity, the ambient temperature, as well as that direct sunlight. Because, again, when it’s ninety-eight ambient temperature, there’s a concern of, well, why are they going out there at ninety-eight if ninety-two is the reading you are supposed to cut off at?”
– Dr. Kechia Rowles, Director of Athletics & Head Athletic Trainer, Rockdale County Public Schools
WBGT typically measures lower that ambient temperature and heat index. This discrepancy can lead to confusion among uneducated coaches or parents.
The GHSA WBGT Zones
Georgia uses a single statewide chart with five zones, and every practice is measured against it.
Source: GHSA By-Law 2.67 – Practice Policy for Heat and Humidity (2025–2026).
A rapid cooling zone, cold water immersion or an equivalent method, is required once conditions cross into elevated territory, and ice towels and spray bottles filled with ice water should be on hand well before that.
Conditioning activities can never be used as punishment, a detail written directly into the bylaw after the fatality data showed how often that pattern preceded a death.
Measurement Requirements
WBGT monitoring is required at every practice through October 1, using a scientifically-approved instrument. Readings start 30 minutes before activity begins and continue at least every 30 minutes throughout. A handheld device needs 15 to 20 minutes outside to stabilize before the first reading counts.
One rule catches schools off guard every season: the zone is locked in at the moment practice starts, not adjusted as conditions change.
“One caveat that in the state of Georgia we had to clarify: when you start a practice, that is where you’re locked into that practice. So if you’re teetering on a yellow, red, or an orange-red, wherever you start practice, that’s where your practice time starts. If you are at an orange and you go to a yellow, you don’t get unlimited practice time. You’re still locked in to those two hours.”
– Dr. Kechia Rowles, Director of Athletics & Head Athletic Trainer, Rockdale County Public Schools
It works the same way in reverse. If conditions worsen mid-practice and a team crosses into a shorter time cap, the clock that mattered was the one running since the team left the locker room, not the one at the new, hotter reading. Practice time starts the moment athletes are exposed to conditions outside, whether or not the whistle has blown.
Cooling, Hydration, and Rest
Once WBGT crosses into elevated territory, an ice bath or cold immersion tub has to be available and ready to go. Jeff Hopp was specific about what “ready” actually means:
“Best practice, honestly, is get the tub filled with water, have the ice sitting off to the side, have it ready to go in case you need it. If you put that ice in at the beginning of practice thinking you’re gonna be good, then by the time you need it, that ice may be gone. So keep the ice sitting off to the side in coolers, have the tub ready to go, and if you have to use it, get the athlete in and then dump the ice in, and continually stir that water to keep it moving.”
– Jeff Hopp, Director of Sports Medicine, Marietta City Schools
Hydration has no on-off schedule. Athletes need access to water at all times, not just during a designated water break, whether that means a trough on the sideline or misters on the field. A rest break means off the field, helmets off, in the shade, with time to actually cool down, not a pause between drills.
Cooling time itself varies enormously by athlete size, a point Dr. Martin has seen firsthand working the Falmouth Road Race for four years alongside Dr. Casa and Dr. Robert Huggins of the Korey Stringer Institute:
“We had an Olympian who weighed ninety pounds cross the finish line and collapse. She had heat stroke, and it only took us eight minutes to cool her to a safe level. But then you think of someone who might be a defensive lineman, and Korey Stringer had it in his contract that he couldn’t be under three hundred and thirty pounds. You take someone like that, and it’s gonna take thirty to forty minutes in an ice water tub to cool.”
– Dr. David Martin, Director of Science, Perry Weather
That range is also why constant monitoring in the tub matters more than a fixed timer, and why coordinating with local EMS ahead of time is worth doing before, not during, an emergency. In some states, EMS cannot remove an athlete from a cold water immersion tub until the athletic trainer confirms it is safe to do so.
Heat Acclimatization
Everybody goes through acclimatization, regardless of how much conditioning a team did over the summer. Jeff Hopp explained why the rule doesn’t bend for teams that trained all season:
“We have to make rules for the lowest common denominator. Not all teams are out there working out all summer long, and not all kids are out there all summer long.”
– Jeff Hopp, Director of Sports Medicine, Marietta City Schools
Marietta’s schedule: 1.5 hours on day one in helmets only, 2 hours on day two in helmets only, 2.5 hours on day three with helmets and shoulder pads, full pads on day four, and full pads or a game on day five.
Hopp helped run the original UGA research behind the rule and said most heat illnesses concentrated in that first week of practice; once athletes were acclimatized, the rate of heat illness dropped sharply. Re-acclimatization applies the same way to any athlete who misses five or more consecutive days, whether from illness or any other reason, since a deconditioned body loses those adaptations quickly.
What Happens When Conditions Change Mid-Practice
The most common question both panelists get is what to do when a reading flickers between zones, a cloud passes over, the meter reads black for a moment, then drops back to red as the sun returns. Does that trigger a full cancellation, or does a 30-minute cumulative average govern the call?
Dr. Rowles’s guidance ties back to the same lock-in principle: whatever zone a team is in when practice starts, and whatever the readings show across each 30-minute check, is what governs that session. A brief spike that resolves is not treated the same as a sustained one. The larger point both panelists made is that schools should be planning around the forecast rather than reacting to it in real time, using multi-day forecasting tools to pick practice windows in advance instead of hoping a reading holds.
Do the Rules Change for Games?
Yes, and it is the question Jeff Hopp hears most often from athletic directors.
Practices. The zone chart’s time caps and equipment restrictions are mandatory. Above 92.0°F, there is no outdoor practice.
Competitions. Games are allowed to continue even above the practice time limits, because players get considerably more built-in downtime during a game than during practice, and by game day, most teams are already through the acclimatization window. That does not remove the cooling requirement:
“The big thing there, though, is please, please, please make sure you have a cold tub set up if WBGT is over eighty-six even on game day. If the kickoff is over eighty-seven, we are mandating more breaks and more downtime. Officials know this.”
– Jeff Hopp, Director of Sports Medicine, Marietta City Schools
The key takeaway for competitions: the rapid cooling zone requirement does not go away because it’s a Friday night instead of a Tuesday practice.
How Perry Weather Helps Georgia Schools Stay Compliant
GHSA requires a scientifically-approved instrument at every practice through October 1, which rules out relying on a phone weather app alone. A Perry Weather station carries a physical WBGT sensor on-site, satisfying that requirement directly, and it logs every reading automatically, so schools can pull the exact reading at the exact time a modification was made without anyone digging through a notebook.
A newer heat stress card in the platform shows coaches, at a glance, which GHSA zone conditions are in right now, plus a forecast of where WBGT is headed over the next three days for planning purposes. Policies are configured to match GHSA’s zone chart directly, so when a threshold is crossed, coaches get the specific required action on their phone, not just a number they have to interpret themselves.
Dr. Martin summed up why that hand-off matters:
“Athletic trainers really are superheroes. They’re doing a million things at once. If you can utilize a platform that limits their role in needing to go out, set up a device, and keep reading it, it allows them to focus on the athlete and making sure everyone’s safe.”
– Dr. David Martin, Director of Science, Perry Weather
If you want to see what automated WBGT monitoring looks like on your fields, get a quote today.
