New Experimental Heat Advisory/Warning Criteria for Broward County

...The National Weather Service Miami Forecast Office Will Test New Heat Advisory and Excessive Heat Warning Criteria for the 2024 Heat Season...

Beginning July 1st, the National Weather Service Weather Forecast Office in Miami (WFO Miami) will test a change to the Heat Advisory and Excessive Heat Warning criteria for public forecast zones in Broward County. This change is in conjunction with the current pilot project in Miami-Dade County which has been in place since 2023. The new criteria for Broward County are better aligned with local climatology, as well as recent health data which indicate that significant health impacts from heat occur at heat index values lower than the current advisory/warning criteria.

Broward County will now have the same heat advisory/excessive heat warning criteria as Miami-Dade County (Table 1), which is as follows for each public zone in those counties:

Heat Advisory: Heat Index of 105F or higher for at least 2 hours
Excessive Heat Warning: Heat Index of 110F or higher for at least 2 hours

UGC Forecast Zone Number	Weather Forecast Zone Name
FLZ073	Inland Miami-Dade
FLZ074	Metro Miami-Dade
FLZ173	Coastal Miami-Dade
FLZ174	Far South Miami-Dade
FLZ071	Inland Broward
FLZ072	Metro Broward
FLZ172	Coastal Broward

Table 1: Universal Geographic Codes (UGC): Weather Zones included in the new Heat Advisory/Excessive Heat Warning Criteria

The new, experimental criteria for Broward County, which will match the existing Miami-Dade County criteria, is based on local temperature climatology and frequency of heat index values at or above the newly defined criteria. The new criteria better align with the historical frequency of heat index values above the newly defined criteria, and is closer to heat index values at which significant health impacts from heat can occur.

The remaining WFO Miami public forecast zones below (Table 2) will continue with the existing heat advisory/excessive heat warning criteria (Heat Advisory - Heat Index 108F or higher for at least 2 hours; Excessive Heat Warning - Heat Index 113F or higher for at least 2 hours):

UGC Forecast Zone Number	Weather Forecast Zone Name
FLZ063	Glades
FLZ066	Hendry
FLZ067	Inland Palm Beach
FLZ068	Metro Palm Beach
FLZ069	Coastal Collier
FLZ070	Inland Collier
FLZ075	Mainland Monroe
FLZ168	Coastal Palm Beach

Table 2: Universal Geographic Codes (UGC): Weather Zones included in the current Heat Advisory/Excessive Heat Warning Criteria

Evaluation of this experiment will take place during and after the 2024 heat season to determine if these changes will become official policy in future years for parts or all of the WFO Miami service area.

For any questions, please contact:

Robert Molleda, Meteorologist-in-Charge

Robert.Molleda@noaa.gov, 305-229-4522 ext. 222

Image 1: New Heat Advisory/Excessive Heat Warning Area in Red, and entire WFO Miami County Warning Area in white with red outlines. UGC public zone numbers inside the zone boundaries