We sat down with Derek Farrey, who oversees athletics for Loudoun County Public Schools in Leesburg, and Dr. David Martin of Perry Weather to walk through what VHSL requires and what it looks like to actually run this policy across a district with two athletic trainers covering dozens of teams. Here is what they covered.
The History of Heat Illness in High School Athletics
Between 1980 and 2009, there were 159 heat stroke fatalities among youth, high school, and collegiate players. Researchers who studied a sub-sample of 61 of those deaths found that 100 percent occurred during conditioning drills, 97 percent of the victims were linemen, and 37 percent were being conditioned as punishment.
Dr. Martin illustrated that difference with an account from Kelci Stringer, widow of NFL player Korey Stringer, who died of heat stroke in 2001:
“She told me he was always the last one to leave the locker room, and she asked him why. It was because it always took him so much longer to cool down. We know this from cold water immersion: the larger someone is, the longer they have to stay in the tub.”
– Dr. David Martin, Director of Science, Perry Weather
The Georgia Study That Started It All
The research that turned this data into working policy came out of Georgia. Andrew Grundstein and colleagues proposed breaking WBGT into risk categories, and at each threshold, requiring specific changes: more rest, more hydration breaks, less total practice time. Once Georgia schools implemented that system, heat-related illness fell more than 30 percent in the lowest risk category, nearly 80 percent in the next, and a full 100 percent in the highest-risk range.
That result is a large part of why WBGT-based policy has since spread state by state, Virginia’s included.
What is Wet Bulb Globe Temperature?
A phone’s weather app shows ambient temperature, air temperature alone, and it doesn’t account for how a body handles exercise in that air. Heat index adds humidity, but the underlying formula was built around someone walking in the shade in long clothing, not an athlete in direct sun. It leaves out solar radiation and exertion entirely.
| 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. |
WBGT, developed by the military in the 1950s after a wave of heat-related illness and death during boot camp training, combines four factors instead of one or two: air temperature, humidity, wind speed, and solar radiation, weighted heavily toward how well a body can evaporate sweat to cool itself.
The VHSL WBGT Zones
Virginia’s policy, developed jointly with VHSL’s Sports Medicine Advisory Committee (SMAC), uses six levels rather than the four or five seen in most neighboring states, with duration caps, fluid targets, and equipment rules that tighten at each one.
Source: VHSL Heat Policy.
Derek Farrey described how that chart actually plays out on a Loudoun County practice field, including a restriction that goes beyond what the chart technically requires:
“At level five, there’s no headgear, no sport-specific equipment: t-shirt, shorts, light breathable material. And for our cross country runners at that threshold, we don’t allow them to practice off campus, even though a lot of programs go to different parks to get their mileage in.”
– Derek Farrey, Athletic Director, Loudoun County Public Schools
At Level 6, the response isn’t just stopping activity outdoors; it includes what happens next. Loudoun County brings athletes inside and keeps monitoring them through the transition, since a team that started practice outdoors and moved inside once WBGT crossed 90°F is still recovering from whatever heat stress it already accumulated.
Measurement Requirements
VHSL’s own guidance is direct about which number governs a decision: WBGT, not air temperature alone, is the preferred index, and real-time, on-site evaluation at the actual activity location is the standard. Heat index may only be used when WBGT monitoring equipment isn’t available, and forecasting tools or mobile apps can support planning but can’t substitute for an on-site reading once activity is underway. Whichever of the six levels the resulting WBGT reading falls into is the one that governs.
Derek Farrey walked through how that standard actually evolved at his own district over roughly three decades:
“Our athletic trainers aren’t around all the time, especially for out-of-season practice. So we made the investment in a Perry Weather station on each of our high school campuses, which was huge for us: all our coaches have access to WBGT even when there’s no athletic trainer on site to measure it themselves.”
– Derek Farrey, Athletic Director, Loudoun County Public Schools
Emergency Action Plans, Cooling, and the Cool-First Protocol
A written EAP is required at every venue, and VHSL provides a template for programs that need a starting point. Relevant personnel must be trained in preventing, recognizing, and treating heat-related illness, and suspected heat stroke requires immediate whole-body cold water immersion in a tub kept between 35°F and 58°F. If a tub isn’t available, cold water dousing, rotating ice towels or bags, and fans are the fallback. Cool first, transport second, is written into the policy, not left as a judgment call.
Dr. Martin relayed a story from Dr. Douglas Casa of the Korey Stringer Institute that shows why the emergency action plan has to account for exactly where an athlete might be, not just what to do once they’re found:
“Doug Casa was a student athlete himself, and his cross country team was taken to a bridge, a very long bridge, to run. A teammate had a heat-related illness incident in the middle of that bridge. If you’re practicing your emergency action plan, that’s a genuinely difficult place to help someone, compared to helping someone on campus with a plan you’ve actually rehearsed there.”
– Dr. David Martin, Director of Science, Perry Weather
That’s part of why Loudoun County doesn’t let cross country teams leave campus once conditions cross certain thresholds. It also shapes how the district handles the decision of when an athlete showing signs of heat stroke actually needs to go to the hospital.
Every school in the district keeps a tarp for the TACO method and either a tub or a Polar Pod on hand for cold water immersion, along with enough coolers and ice to back it up. For a large cross country invitational, that once meant renting a refrigerated storage unit stocked with a hundred bags of ice, not because conditions were forecast to cross the cancellation threshold, but because being prepared for the possibility mattered more than the odds.
Heat Acclimatization and Return-to-Play
Acclimatization is gradual by design. Athletes must be acclimatized to heat over a 7 to 14 day period, and the first 3 to 5 days of preseason practice carry the highest risk and call for the most conservative approach; equipment introduction should be modified or delayed on high heat and humidity days, and pre-participation exams should screen for heat-illness risk factors and prior history. VHSL’s out-of-season practice structure means most athletes are conditioning year-round rather than starting from zero each fall, but the acclimatization clock still applies once official practice begins: helmet only for the first three days, then helmet and shoulder pads, building toward full equipment as the days progress.
Return-to-play timelines differ by condition, not a single blanket rule.
- Muscle cramps. Same-day return once cramps resolve and fluids are replaced.
- Heat syncope. Return after rest, fluid replacement, and symptom resolution; medical clearance advised.
- Heat exhaustion. A minimum of 24 to 48 hours before returning, with a gradual return and medical clearance strongly recommended.
- Heat stroke. Extended rest and hydration, plus a formal medical evaluation, required before any return to activity.
Medication history matters more than it might seem. Derek Farrey noted that in two recent transport cases, both athletes were on medication the school didn’t know about at the time:
“Both of them were on medication we weren’t necessarily aware of, fighting a cold and working through it. That’s something the parent needs to tell us, because certain medications can impact an athlete’s ability to regulate their own core body temperature.”
– Derek Farrey, Athletic Director, Loudoun County Public Schools
Cross country runners get individualized treatment within the acclimatization framework based on documented summer mileage and experience level, since a freshman and a senior with years of logged summer training don’t carry the same risk on day one of the season.
Band, and Small Schools Without a Trainer: What Are the Options?
Marching band isn’t exempt from Loudoun County’s monitoring, even though VHSL’s policy is written primarily around athletics. Derek Farrey described treating band the same way as any outdoor team:
“We’ve actually been monitoring band for quite a while. At level five, we tell our marching band directors that all participants need to be in t-shirts and shorts. At level six, we bring them inside too. We treat them just like our athletes: water breaks at the proper increments, same as everyone else.”
– Derek Farrey, Athletic Director, Loudoun County Public Schools
The harder problem is staffing. Loudoun County now runs two athletic trainers per high school, but for years ran just one, and a single trainer can’t be at football practice and marching band rehearsal and a JV game at the same time. Automated alerts solved a real gap: a trainer dealing with an injured cheerleader indoors no longer has to be the one who personally notices a threshold has been crossed outside.
Virginia doesn’t require every high school to have an athletic trainer at all, and Derek Farrey was candid that many smaller districts don’t have one:
“I have friends in smaller school divisions who don’t have athletic trainers at all, so they don’t have a mechanism to communicate when they’re hitting these thresholds. Coaches are monitoring it through an app on their phone, sometimes WeatherBug, sometimes the OSHA heat index app. It’s fairly accurate, but it’s only heat index. You’re not getting the gold standard for how you actually mitigate risk.”
– Derek Farrey, Athletic Director, Loudoun County Public Schools
For a program without a dedicated trainer, the gap isn’t policy knowledge, it’s the mechanism to act on a reading consistently once conditions change and no one with athletic training experience happens to be standing nearby.
How Perry Weather Helps Virginia Schools Stay Compliant
A Perry Weather station on each campus measures WBGT continuously and on-site, removing the dependency on a trainer physically walking out with a handheld device every 5 to 10 minutes. Alerts go out automatically to every coach based on the exact thresholds a district sets, the same way a lightning alert reaches a cross country team practicing off-site without anyone needing to relay it by text.
The same platform Loudoun County uses for WBGT also covers cold-weather guidelines and air quality, useful for districts managing athletes with asthma alongside heat risk, all from one source instead of coaches checking multiple apps and getting multiple, sometimes conflicting, numbers.
If you want to see what automated WBGT monitoring looks like on your campus, get a quote today.
