The Wet Bulb Globe Temperature (WBGT) is not quite the same as heat index. The WBGT is taken in the Sun to account for the intensity and angle of the Sun’s energy striking the Earth. It also uses wind measurements to get a more accurate picture of how people respond to hot weather conditions. The colored flags indicate the level of heat stress danger.
| Category | WBGT°F | WBGT°C | Flag Color |
|---|---|---|---|
| 1 | <= 79.9 | <= 26.6 | White |
| 2 | 80 - 84.9 | 26.7 - 29.3 | Green |
| 3 | 85 - 87.9 | 29.4 - 31.0 | Yellow |
| 4 | 88 - 89.9 | 31.1 - 32.1 | Red |
| 5 | => 90 | => 32.2 | Black |