HOUSTON — UIL member schools will be required to use Wet Bulb Globe Temperature, or WBGT, to monitor conditions during outdoor UIL athletics and marching band activities beginning with the 2026–2027 school year.

UIL has recommended the WBGT system since 2023. The major change is that using the measurement and following the practice modifications tied to it will become mandatory beginning Aug. 1.

WBGT accounts for temperature, relative humidity, wind speed and solar radiation. Schools use the reading to determine whether they need to add rest and hydration breaks, limit protective equipment, shorten practices or stop outdoor workouts until conditions improve.

Schools must check the WBGT 15 minutes before practice begins and again every 30 minutes during practice. They may use an on-site WBGT instrument or another scientifically proven method, including an internet-based weather application. When the reading moves from one level to another, schools must adjust practices according to UIL’s activity guidelines.

UIL divides areas into heat classifications based on climate. Houston falls within Class 3, meaning local schools follow the Class 3 column of the WBGT activity chart.

In Class 3 areas, a rapid-cooling zone is required once the WBGT reaches 82. Those zones must provide immediate access to a cold-water immersion tub or a tarp that can be filled with ice and water to rapidly cool someone experiencing heat illness.

As WBGT levels rise, the required practice modifications become more restrictive. Those changes can include longer rest periods, shorter workouts and limits on the equipment athletes wear. At the highest level, outdoor workouts cannot continue until a lower WBGT reading is reached.

The numbers on the chart are WBGT readings—not the air temperature or heat index.

UIL also says student-athletes must have unrestricted access to water and should never be denied water. Rest breaks must include unlimited hydration and no physical activity.

The practice limits do not apply automatically to UIL competitions. However, schools are encouraged to monitor conditions during games and consider safety changes such as additional timeouts, adjusted start times, shade, misters and longer halftimes. A rapid-cooling zone is still required at a contest when the applicable WBGT threshold is reached.

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