When your team is working or training outdoors, assessing heat conditions involves more than simply looking at the temperature on your weather app. Wet bulb globe temperature helps explain why an 80°F day can feel manageable in one setting and dangerous in another. It captures the conditions that drive real heat strain, not just what a standard thermometer reports.
For executives responsible for safety, WBGT provides a clearer way to assess heat-stress risk and adjust operations before conditions become dangerous. In this guide, you’ll learn what WBGT is, how it differs from other “feels like” metrics, and how to interpret readings to support better work-rest decisions and heat controls.
Learn how TempestOne supports heat-risk decisions with better site-specific weather intelligence.
What Is Wet Bulb Globe Temperature?
WBGT is a heat-stress index designed for real-world exposure. It blends several environmental inputs into one value that better reflects how the body experiences heat during exertion, especially in direct sunlight.
WBGT accounts for air temperature, humidity, solar radiant heat, and wind. Those factors interact in ways that can quickly raise risk. High humidity can limit sweat evaporation, strong sun can add radiant load, and low wind can reduce cooling. The result is a metric that better aligns with how quickly people can overheat.
You may also see WBGT written casually as wet bulb globe temp. Regardless of the shorthand, the goal is the same: move from “it’s hot” to “how much heat stress is this environment creating right now?”
Wet Bulb Globe Temperature Vs. Wet Bulb Temperature
Wet-bulb temperature focuses on evaporative cooling, or how effectively sweat can cool the body at a given humidity level. That’s useful, but it doesn’t capture the full heat load someone faces from the sun or from radiant surfaces.
WBGT adds those missing pieces. It incorporates radiant heat and airflow effects to provide a broader assessment of heat stress. If your safety decisions involve sun exposure, heavy work, or variable wind, wet bulb temperature alone can understate the risk.
Wet Bulb Globe Temperature Vs. Heat Index
The biggest difference between the WBGT and the Heat Index is context. Heat index is designed for shaded conditions and generally assumes light physical activity. It combines air temperature and humidity, but it does not include direct sun or wind impacts.
WBGT is often preferred when people are working, training, or competing outdoors, because sunlight and airflow materially change heat stress. Two days can share the same heat index while WBGT diverges due to different wind, cloud cover, or solar intensity. That is why many safety programs rely on WBGT thresholds.
Read our Weather Risk Assessment guide for a multi-hazard approach to monitoring weather-driven safety risks.
How To Read And Interpret The WBGT
The wet-bulb globe temperature calculation has multiple inputs, often including a “natural” wet-bulb temperature, a globe temperature representing radiant heat, and a standard air temperature. Some tools also incorporate sun angle and cloud cover to better represent solar radiation.
For decision-making, the key is treating WBGT as a risk signal, not a trivia metric. As WBGT rises, the body stores heat faster, especially during moderate to heavy work. That should trigger practical controls like modified schedules, shaded breaks, hydration planning, and closer symptom monitoring.
Below is a practical way to interpret WBGT ranges. Exact thresholds vary by policy, acclimatization, clothing/PPE, workload, and local standards, so your safety plan should reflect your workforce and conditions.
|
WBGT range (°F) |
What it generally indicates |
Operational response ideas |
|
Below 80 |
Lower heat strain for most people |
Normal operations with hydration reminders |
|
80–85 |
Heat strain builds with sustained effort |
Add structured breaks and reduce peak exertion |
|
85–88 |
Higher risk during physical work in the sun |
Increase rest time, cooling access, and active supervision |
|
88–90 |
Very high heat stress risk |
Shorten work bouts, limit heavy tasks, and elevate medical readiness |
|
Above 90 |
Extreme risk for many situations |
Consider postponing strenuous work or moving tasks indoors |
The most important nuance is location. WBGT can change across microclimates, surfaces, and shade lines. A reading a mile away may not match the conditions on your site. That’s why organizations pair thresholds with accurate, on-site monitoring and clear action triggers.
TempestOne: A Professional Weather Risk Solution
WBGT is most useful when it is timely, local, and easy to act on. If your operations depend on outdoor activities, athletics, or heat-sensitive schedules, better weather intelligence can support safer staffing decisions, shift timing, and heat controls to prevent heat-related illnesses.
TempestOne is designed to help businesses make weather-driven decisions with more confidence, including heat-risk planning that goes beyond generic forecasts. When you can see conditions at the site level, you can respond earlier and reduce disruption while protecting people.