The Texas UIL Just Made WBGT Mandatory: What the 2026-2027 Heat Rule Requires

For three seasons, using Wet Bulb Globe Temperature to run your practices was a strong recommendation. As of August 1, 2026, it's the rule.

The UIL has moved WBGT from recommended to required for every outdoor athletic and marching band activity in the 2026-2027 school year. The Medical Advisory Committee pushed the change after two years of recommended use, and the Legislative Council approved it. If you coach or run a program in Texas, how you monitor heat is no longer left to interpretation.

This is the right move, and it changes what compliance looks like starting at fall camp. Here's what the mandate requires, why the science backs it, and the one job it was never built to do.

What the mandate requires

WBGT estimates the combined effect of temperature, humidity, wind speed, and solar radiation using three thermometers. That makes it a sharper read of the field than the heat index, which only weighs temperature and humidity.

Starting this school year, UIL member schools must build their outdoor sessions around it. The core requirements:

• Measure it correctly: Use a scientifically approved WBGT instrument or an approved internet-based method. Take the reading within 15 minutes before practice, then every 30 minutes during. On-site devices should be set up 30 minutes ahead.
• Modify by level: Adjust work-to-rest ratios, hydration breaks, equipment worn, and practice length based on the WBGT reading and your region's classification (Texas UIL Class 2 or Class 3).
• Stage cooling on site: A rapid cooling zone with cold-water immersion is required once WBGT reaches the mandated threshold for your class, for practices and contests alike.
• Keep water open: Unrestricted access to water at all times. An athlete is never denied water, and rest breaks mean rest, with unlimited hydration and no activity.

Your region's class comes from the UIL WBGT map. The UNC forecasting tool lets you enter your exact practice location and select your class to see the live reading and the matching activity guidelines.

Why the science backs the new rule

The heat index was built for shade. On an open field in full sun, it misses two of the factors that decide how hot the day plays: radiant heat coming off the turf and the wind that does or doesn't carry it away. WBGT folds both in, which is why it flags dangerous conditions the heat index reads as merely uncomfortable.

The cold-water immersion requirement is just as well grounded. Cold-water immersion is the peer-reviewed gold standard for rapid cooling, and every minute of delay raises the risk. Cool first, transport second. A cooling zone staged before the session is what makes that response possible in the minutes that matter.

The one thing the standard can't do

WBGT describes the field. It produces one number for everyone standing on it. What it can't describe is the athlete.

There is no universal critical core temperature. Athletes have been recorded tolerating core temperatures that would drop a teammate, which is why population-level cutoffs miss the cases that matter most. Sweat rates alone vary significantly between two athletes in the same session. The conditions are shared but the response is individual.

None of that is an argument against the mandate. Heat illness due to exertion is one of the leading causes of preventable death in sport, and research shows most programs still don't run the full evidence-based protocol. The mandate closes part of that gap at the field level. The rest of the gap lives at the level of the individual athlete.

Build on the mandate: a four-tier approach

The strongest programs treat WBGT compliance as the base of a stack, not the whole of it. Think of heat management in four tiers, each one adding a layer the one below can't provide.

• Tier 1, Environmental compliance: WBGT readings on schedule, activity modifications by level, and a staged cooling zone. This is the mandate. It is non-negotiable.
• Tier 2, Individual awareness: Know which athletes carry more load on any given day. Linemen and fully-padded positions, athletes returning from a break, and anyone not yet acclimated deserve closer eyes.
• Tier 3, Individual visibility: Real-time monitoring for the athletes the field number can't account for. Multi-parameter monitoring that combines core temperature, heart rate, and skin temperature identifies individual heat response that a single environmental index misses.⁵ This is where HeatSense gives your staff a live view of each athlete on their own curve.
• Tier 4, Response capacity: Staff ready to act and cold-water immersion prepared before the whistle. Cool first, transport second.

Tiers 1 and 4 are now written into UIL policy. Tiers 2 and 3 are where a coach or trainer turns compliance into a genuine read on the athletes in front of them.

Run it across a season, not a day

August 1 lands the mandate squarely in the highest-risk window of the year. Athletes are most vulnerable to heat before they have adapted to it, and most acclimation gains arrive in the first 5 to 7 days, with full adaptation by 10 to 14 days.

The rule applies every day. Readiness is built over weeks. Run WBGT before every session, ramp intensity and equipment deliberately through the acclimatization window, and keep individual eyes on the athletes still climbing their own curve.

Frequently asked questions

When does the WBGT mandate take effect?

August 1, 2026, for the 2026-2027 school year. It follows two years of recommended use before the Legislative Council approved making it required.

Does it apply to games or only practices?

The activity modifications apply to practices, workouts, and conditioning. The cooling-zone requirement applies to contests as well once WBGT reaches your class threshold.

What's the difference between Class 2 and Class 3?

They are regional classifications that set the thresholds for your area. Use the UIL WBGT map or the UNC forecasting tool and select your class to see the guidelines that apply to you.

Does WBGT tell me if a specific athlete is in trouble?

No. It reads the environment for the whole field, not the individual body. That is why individual monitoring sits on top of the mandate rather than inside it.

Do we really need cold-water immersion on site?

Yes. It is required once you hit your class threshold, and it is the evidence-based method for rapid cooling. Staging it before the session is what lets you cool first and transport second.

The number describes the day, not the athlete

The rule changed because the evidence did. WBGT is a sharper read of the field than almost anything programs used before, and making it mandatory raises the standard of care for every athlete in Texas.

Meet it in full. Then add the one thing a field-level number was never built to give you: a real-time view of each individual athlete, so the staff responsible for them can make the call before the curve turns. See how HeatSense makes individual heat response visible in real time at heatsense.com.

References:
1. Brown, Smallcombe et al., Prehospital Emergency Care, 2023.
2. Racinais et al., British Journal of Sports Medicine, 2019.
3. Périard et al., Physiological Reviews, 2021.
4. Périard, DeGroot & Jay, Experimental Physiology, 2022.
5. Flouris et al., Industrial Health, 2022.
6. Périard, Racinais & Sawka, Scandinavian Journal of Medicine & Science in Sports, 2015.