National Weather Service United States Department of Commerce


The NWS is seeking user feedback on experimental Wet Bulb Globe Temperature (WBGT) grids in the  National Digital Forecast Database (NDFD) through September 30, 2019.

NWS currently uses the Heat Index to convey heat risk during summer heat events. While the heat index is useful for sedentary  populations, research has proven that the WBGT is a more effective means of assessing heat risk to persons involved in physical activity. The WBGT is a composite parameter that estimates the effect of temperature, humidity, wind chill, and solar radiation on humans, while Heat Index only takes into  account temperature and humidity.

Based upon engagement with core partners, particularly emergency  management officials, the NWS has identified the need to provide   WBGT forecasts because it is becoming an increasingly needed  parameter by partners in Impact-based Decision Support Services  (IDSS) activities. In particular, WBGT is important for those  partners who need a numerical (finite) value, rather than a threat index, to determine necessary modifications to their respective activities in the interest of protecting life.To better meet users' needs, NWS will provide gridded forecasts of WBGT in the NDFD on an experimental basis.

NWS Product Description Document for the experimental WBGT forecasts.

Feedback form and survey.