CIF Heat Stress: WBGT Guidelines for CA Schools Explained


CIF Heat Stress: WBGT Guidelines for CA Schools Explained

Mar 6, 2024
Written By
Saba Arif

California schools are taking a stand against heatstroke and heat-related illnesses with a new weapon: on-site WBGT monitoring. If you don’t know what that is, you’ve come to the right place. Keep reading to learn more about how this new mandate helps protect athletes and keeps them performing at their peak!

This in-depth guide explores the impact of WBGT monitoring and school heat safety on athletes and athletic trainers. We’ll also discuss how schools can comply with the new California Interscholastic Federation (CIF) mandate.

The New CIF Mandate: Heat Stress & WBGT Monitoring Policies

The California Interscholastic Federation (CIF) has mandated WBGT monitoring during athletic activities, particularly during high-risk periods of heat exposure (CIF, 2024).

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These heat stress policies in California provide clear protocols for managing heat-related risks to prioritize the safety of student-athletes. Governor Newsom’s Extreme Heat Action Plan allocates resources towards community outreach and education, vulnerability assessments, and establishing cooling centers.

The new bill requires these regulations for all CIF-member schools in California, effective July 1, 2024:

1. Modified Practice Schedules:
– Schools must schedule outdoor practices during cooler times, like early morning or late evening, with frequent breaks and shade.
– Schools must postpone or cancel practices and/or competitions during extreme heat.
– Trainers can gradually increase the intensity and duration of practice sessions over 10-14 days.

2. Monitor Athlete Health:
– Coaches, trainers, and athletes must be trained to recognize the signs of heat exhaustion and heat stroke.
– Student-athletes who display signs of heat illness must be removed from a practice or game and may not return until they have written clearance from a health care provider.

3. Heat Illness Prevention:
– Schools must invest in WBGT monitoring tools like handheld monitors or weather stations to take WBGT readings.
– Schools must have ice baths or special cooling wraps on hand to treat heat stroke and other heat illnesses.
– Coaches and athletes must learn the importance of taking regular water breaks during practice and games and recognizing signs of dehydration.

4. Five-Day Acclimatization Period: 
– Outdoor fall sports have a five-day warm-up and acclimatization period. Practices will be shorter with limited gear for the first few days.

5. Emergency Action Plan:
– Each school must have an emergency action plan in place, with a list of the locations of all on-site emergency equipment, assigned personnel, and post-emergency procedures.
– Plus, at least one automated external defibrillator (AED) must be readily available.

CIF Guidelines

These changes aim to create a safer environment for student-athletes by promoting awareness and making informed decisions on heat stress risks.

The Impact of WBGT Monitoring on Schools and CIF Sports

What Does the New CIF Heat Stress Bill Mean for Athletics in California?

The CIF wet bulb globe temperature mandate impacts schools, athletic trainers, and coaches responsible for athlete safety during practices and competitions. All California Interscholastic Federation (CIF) member schools and athletic programs will have to implement specific on-site WBGT monitoring and heat illness prevention plans based on WBGT readings. The CIF requires that schools use the WBGT for the most accurate measurement.

Schools must invest in WBGT monitoring equipment and train coaches and athletic trainers to interpret and respond to WBGT data effectively.

The CIF specifies outdoor activity guidelines based on environmental conditions in your region and has classified them into three categories as listed in the heat safety table below:

  • Region Category 1 >86.2°F
  • Region Category 2 >89.9°F
  • Region Category 3 >92.0°F

California State WBGT Zone Map

California’s diverse geography calls for a nuanced approach to WBGT monitoring. Different regions experience varying degrees of heat intensity, requiring tailored policies. The wet bulb globe temperature chart lists the state’s WBGT zone guidelines outlining protocols based on regional heat variations, like:

  • Acclimatization: Athletes’ ability to adapt to hot environments improves over time. Zones with higher temperatures acclimatize faster compared to the cooler zones. This is reflected in the differing WBGT thresholds for modifying activities across the zones.
  • Geographic variations: The intensity of heat waves also varies significantly between regions. Southern California typically experiences more frequent and intense heat waves, with higher WBGT thresholds compared to the north.

In Category 3, with its faster acclimatization, activity modifications might be recommended at a WBGT of 82°F (27.8°C), compared to 85°F (29.4°C) in Category 1. Understanding these nuances is crucial for schools to prevent heat illness and ensure athlete safety effectively.

CIF member schools are encouraged to check with their district office to determine which WBGT region they are in.

What is Wet Bulb Globe Temperature?

WBGT (Wet Bulb Globe Temperature) is a wet bulb formula that measures heat stress in direct sunlight by taking into account:

  • Temperature
  • Wind Speed
  • Sun Angle
  • Humidity
  • Cloud Cover

How and When to Use WBGT?

Heat stress happens when the body temperature struggles to cool down. Athletes are particularly susceptible to heat stress during exercise. Traditional methods, such as air temperature alone, are insufficient for assessing heat stress risks. This is where WBGT (Wet Bulb Globe Temperature) comes in.

Unlike the heat index, which focuses on air temperature and humidity, WBGT offers a holistic assessment of the environment, making it the preferred method for determining safe outdoor activity levels for athletes engaged in physical activities. 

Heat Index vs. WBGT: Why the “Feels Like” Doesn’t Tell the Whole Story

The heat index falls short of assessing heat stress risks for outdoor activities. The Heat Index mainly considers air temperature and humidity, neglecting factors like wind speed, sun angle, and cloud cover. A WBGT meter addresses these limitations by offering an accurate assessment of environmental heat stress and its impact on the human body.

How Does WBGT Impact Athletes?

A higher WBGT reading leads to a greater risk of heat-related illnesses like heat stroke, heat exhaustion, and muscle cramps.

Monitoring WBGT is essential for protecting athletes’ health and safety during outdoor practices, games, and events.

You can measure WBGT using handheld devices known as WBGT monitors, on-site weather stations, or through online weather WBGT apps. These devices incorporate temperature, humidity, and solar radiation sensors to calculate wet bulb temperature and the WBGT index. Regular monitoring of WBGT levels allows coaches and athletic trainers to adjust training schedules, implement hydration protocols, and make informed decisions.

As athletes exert themselves, their bodies generate heat that they need to expend to maintain a safe internal temperature. When environmental conditions, such as high humidity or limited air movement, hinder heat evaporation, WBGT rises.


California’s AQI Guidelines: Impact on Schools

Air pollution poses serious health risks, impacting students, especially those with asthma or other respiratory conditions. To address this pressing concern, the California Air Resources Board (CARB) has implemented a series of stricter Air Quality Guidelines for Schools and introduced new monitoring requirements.

WBGT Solutions and Technologies

Ensuring accurate and reliable WBGT monitoring is crucial for safeguarding athletes from heat stress and poor air quality. While various options exist, each carries advantages and limitations. Understanding these differences is essential for schools and athletic programs to choose the best solution for their specific needs.

Here’s a breakdown of the most common WBGT monitoring methods:

Handheld WBGT Monitor


This portable wet bulb globe temperature device offers quick readings, making it an easy option for athletic trainers and coaches overseeing outdoor activities.

However, it often displays inconsistent and inaccurate readings and requires a lot of manual adjustments.

Portable: Convenient for taking measurements on the goLack of Accuracy: It features a small 1-inch black bulb sensor for WBGT monitoring. However, a sensor of that size often leads to inaccurate readings compared to larger, professional weather stations.
Durable: Designed for outdoor useManual operation: Requires user to take readings manually, increasing the risk of human error.
Limited features: Doesn’t offer features like real-time monitoring, historical data logging, or customizable alerts.
Lack of Policy Integration: Doesn’t support customizing policies for seamless organizational policy integration, requiring additional manual effort.
Limited Connectivity: Relies on WiFi and Bluetooth connectivity for updates, which may not always be reliable, especially outdoors.
Cost: While cheaper upfront, ongoing costs might be higher as it needs frequent calibration

Free Weather Apps and Websites


Several free weather apps offer estimated WBGT readings based on local weather data.

While convenient and accessible, these estimates may not be as accurate, fast, or site-specific as weather stations.

Cost-Effective: No initial cost to download the app or access the website.Lack of Accuracy: Does not offer hyperlocal on-site weather data and hence the estimated WBGT readings might not be accurate for your specific location. 
Accessibility: Offers basic weather information on most smartphones.No Real-time Updates: Free apps like Weather Bug also source weather data that is delayed by several minutes, making it an unreliable and potentially dangerous weather safety monitoring solution.
Limited Features: Lacks crucial features like customizable alerts, historical data logging, and WBGT forecasts.
Lack of Policy Integration: Doesn’t support customizing policies for seamless organizational policy integration, requiring additional manual effort. 

On-Site Weather Stations

There are many types of weather stations with significant variations in quality and reliability.

On-site weather stations like Perry Weather provide WBGT data alongside other weather parameters. This option can be cost-effective and presents more accurate, real-time readings, and is ideal for continuous monitoring.

Accurate Readings: Precise, automated WBGT readings every 15 minutes, eliminating the need for manual temperature measurements and reducing the risk of human error.Higher cost of entry compared to general-purpose weather monitoring devices
Custom Alerts: Customizable alerts for heat stress, lightning, and custom triggers or manual warnings.
Real-Time Weather Data: Continuous monitoring for real-time data and proactive decision-making.
Hyperlocal Precision: Precise, accurate, on-site data in real-time, WBGT and Heat Stress Monitoring
Historical Log: Historical data log to analyze WBGT trends for informed planning.

How Perry Weather Can Help

Accurately monitoring weather conditions, particularly heat stress, can be a challenge. Traditional handheld tools like Kestrels are often inconsistent and require additional setup, leading to potential inaccuracies. This is where Perry Weather steps in. Perry Weather’s user-friendly solution empowers schools to confidently monitor weather conditions and prioritize athlete safety.

Here’s how Perry Weather stands out from the competition, specifically Kestrels:

Easily comply with historical WBGT readings

Perry Weather automates monitoring Wet Bulb Globe Temperature (WBGT) by recording values every 15 minutes, so you’ll never need to manually log or take notes ever again.

Actionable, Policy-Based Alerts

Perry Weather instantly sends clear, actionable alerts based on WBGT zone guidelines, so athletic trainers always know that their students are safe.

Single Source of Truth

Perry Weather’s weather monitoring platform allows an entire school district to rely on a single platform for consistent weather data, leaving no room for discrepancies.

Make Informed Decisions with 24/7 Meteorologist Support

Perry Weather’s meteorologist team is available 24/7 for expert guidance and planning support via email, phone, or text.

Radiation Shield for Accuracy:
Sunlight and other external heat sources can skew handheld monitor readings. Perry Weather stations combat this with an integrated radiation shield, guaranteeing measurements are not influenced by these factors. This ensures unmatched precision compared to Kestrels that lack this critical feature.

Automated Readings to Eliminate Human Error:
Handheld monitors require frequent calibration and are susceptible to user error when moving between environments. Perry Weather stations automate readings and eliminate the risk of human error, ensuring consistent and reliable data.

Actionable Alerts and Outdoor Warning System:
Perry Weather sends clear and concise instructions based on WBGT zone policies, so coaches know exactly what to do during practices or games. Notifications and warnings can be customized and broadcast via text, mobile app, as well as the outdoor warning system.

With Perry Weather, California schools can comply with CIF regulations and simplify the WBGT monitoring process while prioritizing the well-being of their athletes.


As the focus on weather safety in school athletics intensifies, monitoring WBGT levels is essential to protect student-athletes from heat-related risks. The new CIF mandate puts WBGT monitoring front and center to ensure the safety and well-being of athletes. By investing in reliable wet bulb globe temperature meter monitoring solutions like Perry Weather, schools can tackle these challenges effectively and create a safer environment for student-athletes to thrive.

Learn more about how Perry Weather can help your school comply with the new WBGT policies and ensure athlete safety. Visit our website or contact us today to discuss your specific weather monitoring needs.

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