National Weather Service United States Department of Commerce

Wet Bulb Globe Temperature (WBGT) is a measure of the heat stress in direct sunlight, which takes into account: temperature, humidity, wind speed, sun angle and cloud cover (solar radiation). This differs from the heat index, which takes into consideration temperature and humidity and is calculated for shady areas. For more background info on WBGT, click here.


 

 
  • 101% means summit in and out of clouds
  • 102% means summit obscured
 

 

 

 

 
Lightning Threat represents thunderstorm coverage at any one time in the forecast period.

 

 

 

Lightning Legend         Lightning Safety Tips
 
Risk Level
Definition
None
No lightning risk
Limited
Thunderstorms expected to be isolated in coverage. 
Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be aware for thunderstorms in your area.
Elevated
Thunderstorms expected to be scattered in coverage.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Be prepared to take immediate shelter from thunderstorms and lightning.
Significant
Numerous thunderstorms are expected.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Plan to take immediate shelter from thunderstorms and lightning.
Extreme
Widespread thunderstorms are expected.
  Atmospheric conditions support cloud to ground lightning strikes in and near thunderstorms.
Plan to take immediate shelter from thunderstorms and lightning.