AYSO Region 13 follows California Interscholastic Federation (CIF) heat acclimatization guidelines. We monitor Wet Bulb Globe Temperature (WBGT) at our field locations and adjust or cancel activities based on the alert level. Live readings are available on the Weather and Field Conditions page.
What is WBGT?
Wet Bulb Globe Temperature is a heat-stress measure that combines air temperature, humidity, wind, and solar radiation. It reflects how the human body actually experiences heat during outdoor exertion, which is why CIF and most major youth-sports organizations use it instead of plain air temperature.
WBGT is always lower than air temperature in dry conditions and approaches air temperature in humid conditions. A WBGT of 85°F is roughly equivalent to a hot, sunny, humid afternoon, meaningfully more dangerous than a 90°F dry, breezy one.
Alert levels
| Level | WBGT (°F) | Required action |
|---|---|---|
| 1 | ≤ 79.7 | Normal activities. Provide ample water and unrestricted breaks. |
| 2 | 79.8 – 84.6 | Frequent water breaks, every 30 minutes minimum. Watch carefully for heat illness. |
| 3 | 84.7 – 87.5 | Maximum 2 hours of practice. Four 4-minute water breaks per hour. Lighter clothing. |
| 4 | 87.6 – 89.7 | Practice: maximum 1 hour, four 4-minute water breaks per hour, no equipment. Games: length reduced by one-third, with additional water breaks at the 1/8 marks. |
| 5 | > 89.7 | All outdoor activity suspended. Practices and games are canceled. Region 13 closes fields until conditions cool. |
How we make the call
Region 13 monitors WBGT throughout the day. The current reading and CIF level are visible on Weather and Field Conditions, updated every five minutes from our on-site weather station.
When WBGT crosses into Level 5, the weather page shows a closure banner. The board confirms and posts an official closure to the home page banner via Slack. Notifications go out by 7 AM on game days or 4 PM on practice days when heat alerts are in effect.
If a coach or family judges conditions to be unsafe at any level, they have the final say on individual participation. Either coach in a game may elect not to play in hot conditions without forfeit penalty.
What you can do
- Hydrate before, during, and after. Cold water; sports drinks for longer practices.
- Watch for heat illness signs. Cramping, dizziness, headache, confusion, hot dry skin, stopped sweating, nausea. If you see them, stop the activity, get the player into shade, cool them with water, and call for help. Heat stroke is a medical emergency.
- Speak up. Players, coaches, and families should report conditions to the referee or division coordinator. Earlier is better.
Source
These thresholds and required actions follow the California Interscholastic Federation Sports Medicine Advisory Committee heat acclimatization policy, applied to AYSO Region 13’s program. See CIF State for the original guidance.
Related
- Weather and Field Conditions: live WBGT, current conditions, 7-day forecast
- Rain Policy: wet-field closure thresholds
- Safety: concussion, sudden cardiac arrest, incident reporting
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