Why WBGT, and which region you are in
Wet bulb globe temperature (WBGT) accounts for temperature, humidity, wind and solar load. It is the standard adopted by Georgia, Texas (mandatory for all outdoor practices from August 2026), Missouri, California and others Sourced.
The Korey Stringer Institute's regional categories shift the thresholds downward for cooler climates, because athletes there are less acclimatized Sourced:
- Category 3
- The hottest region: the Southeast and most of Texas.
- Category 2
- Moderate.
- Category 1
- The coolest: the northern tier and the Pacific coast.
The five-zone WBGT table
| Zone | Category 3 | Category 2 | Category 1 | Required action |
|---|---|---|---|---|
| Green | Under 82.0 | Under 79.7 | Under 76.1 | Normal; at least 3 rest breaks per hour, 3 minutes each |
| Yellow | 82.2 to 86.9 | 79.9 to 84.6 | 76.3 to 81.0 | Discretion for intense work; 3+ breaks per hour, 4 minutes each; watch at-risk athletes |
| Orange | 87.1 to 90.0 | 84.7 to 87.6 | 81.1 to 84.0 | Max 2 hours; 4+ breaks per hour, 4 minutes each |
| Red | 90.1 to 91.9 | 87.8 to 89.6 | 84.2 to 86.0 | Max 1 hour; 20 minutes of rest spread through the hour; no conditioning |
| Black | 92.1+ | 89.8+ | 86.2+ | No outdoor activity; delay or cancel |
Source: Korey Stringer Institute policy template; mirrored in GHSA By-Law 2.67 and the Texas UIL mandate Sourced. Missouri uses lower bands for middle school; applying the lower bands to players 14 and under is a reasonable youth adaptation Estimate.
How to measure WBGT
- A handheld WBGT meter costs roughly $150 to $500. Subscription weather services deliver WBGT and lightning alerts together.
- Read 30 minutes before activity and every 30 minutes after.
- Handheld meters need 15 to 20 minutes outdoors to stabilize.
- On turf, read at the surface.
Ready to launch? Flag50 runs registration, your league website and live scoring for independent and affiliated leagues.
Book a 20-minute call →Cooling on site
- Green zone: a cooler of ice and towels at minimum.
- Yellow and above: a cold-water immersion tub, or a tarp with water under 60 F, ready within 5 to 10 minutes of every field.
Game-day changes by zone
- Yellow: add an official's water timeout mid-half.
- Orange: shorten halves and extend halftime.
- Red: cancel, or move to early morning or evening.
- Scheduling: in hot regions, schedule August and September games before 10 am or after 6 pm.
Summer storms have their own rules. The suspend and resume rules for thunder are in lightning and weather policy.
Acclimatization and hydration
The first week of any season or camp is shorter and lighter, with more water breaks, especially in Category 2 and 3 regions.
Keep water accessible before, during and after play, with breaks in shade. Thirst, dark urine and headache are the warning signs every coach should know.
Heat policy checklist
- KSI region category chosen
- WBGT meter or weather service in place
- Five-zone policy published to coaches, officials and families
- Signed heat information sheet from every parent at registration
- Ice, towels, and an immersion tub or tarp on site in hot months
- August and September games scheduled outside the hottest hours