Wet Bulb Globe Temperature... What and Why

Wet Bulb Globe Temperature... What and Why

Season 7 Episode 1

 

Host: Chris Doelle
Co-Host: Brian Polk (COO Texas High School Coaches Association)
Guest: Ray Zepeda - UIL Athletic Director
Dr. Keeli Hanzelka - Dell Children's Hospital

EPISODE SUMMARY: The UIL's WBGT mandate is now in effect for the 2026-27 school year after two years as a recommendation. Ray Zepeda and Dr. Keeli Hanzelka break down what wet bulb globe temperature actually measures, why it matters more than air temperature alone, and how Texas coaches can use it as a practical tool rather than viewing it as another restriction. Texas is roughly the 23rd state to mandate WBGT protocols.

Key Takeaways:
 • What WBGT actually is: Three temperatures in one measurement (air temp at 10%, natural wet bulb at 70%, black globe) that accounts for humidity, wind, and direct sunlight to predict heat stress on the body.
• Military origins: Developed in the 1950s for military training, where it significantly reduced heat illness and death among cadets.
• Why mandate over recommendation: Schools following the voluntary guidelines felt penalized by inconsistent adoption. UIL consulted with Georgia, Florida, and other state associations before moving to a requirement.
• Practices vs. competitions: The mandate applies to practices, not contests, because the data shows almost every serious heat incident in Texas over 20 years occurred during practice.
• Competitive equity and facilities: Indoor facilities do create advantages, but student safety outranks competitive equity. UIL heard from stakeholders that some communities wouldn't invest in heat mitigation until a mandate forced the issue.
• Coaching adjustments: Top programs are adapting creatively with earlier/later practice times, position-specific conditioning, and alternative practice locations (one team used a covered rodeo arena).

Key quotes
• "It's hotter today than it was back then. That's just a verifiable fact. We are more educated than we were at that time. It would be really silly if we aren't using everything that has been learned in order to keep kids safe and maximize their performance." : Ray Zepeda
• "A dry tank overheats faster. Studies show that kids drink 50% more fluids if those fluids are cool as opposed to room temperature or warm." : Dr. Keeli Hanzelka

Links & Resources
• THSCA Heat Toolkit/Playbook: Available on the THSCA website under the Health and Safety tab (developed in partnership with Dell Children's and UIL)

Texas High School Coaches Association (THSCA): www.thsca.com

Texas High School Coaches Association

Twitter:

• @THSCAcoaches
• @ChrisDoelle

Limited sponsorship opportunities are available on the show. Contact Chris Doelle at [phone] or email at [e-mail].

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