textproduct: Miami - South Florida

KEY MESSAGES

Updated at 733 AM EDT Thu Aug 20 2026 - Slightly lower high temperatures expected today but heat indices of 105-110 are still anticipated this afternoon. Heat Advisory in effect from 11AM to 6PM.

- Scattered thunderstorms expected after midday this afternoon and into the evening will provide some relief from the heat.

SHORT TERM

(Today through Friday) Issued at 109 AM EDT Thu Aug 20 2026

As the Saharan dust continues to filter out of the area for the end of this week, deeper moisture will simultaneously begin to work back into South Florida for the end of the week as a couple of upper level disturbances in the Caribbean help infiltrate extra tropical moisture. These upper level lows are not expected to reach South Florida, but will still provide this deeper moisture advection. Similarly, an upper-level trough will enhance underneath strong jet dynamics as a result of a stout ridge across the Southwestern US. As the trough deepens and digs southwards, prevailing wind flow will shift to more of a southerly direction across the forecast area. This will result in a pooling of the deep moisture for the end of this week and likely beyond.

As a result of the pattern above and the dissipation of the dust plume, temperatures should fall closer to normal in the low to mid 90s for today and tomorrow while convection also initiates a couple hours earlier and starts to become more widespread in the afternoon and evening hours. Given the prevailing southwesterly flow today and eventually southerly flow on Friday and into the weekend, the Atlantic sea breeze will not advance as far inland as it typically does, which is expected to result in the more widespread coverage of showers and thunderstorms to occur across Southeast Florida. Some storms will be capable of producing strong wind gusts as high as 40- 50 mph but severe parameters are rather limited for this end of of week time period. Main concerns will be for heavy rainfall lowering visibilities on roadways, strong wind gusts and localized flooding as a result of training storms or convection re-developing over the same locations.

In terms of heat, it should not be quite as hot as the last couple of days given the dust plume dissipating. However, with deeper moisture arriving there will still be dew points in the upper 70s for most of the region and high temps achieving the low to mid 90s prior to rain occurring across the region in the afternoon. Therefore, opting to go with a Heat Advisory again for today from 11AM - 6PM for all of South Florida. If rainfall becomes widespread earlier than 6PM and causes sudden decreases in heat levels, then this advisory could be canceled prior to 6PM.

LONG TERM

(Friday night through Wednesday) Issued at 109 AM EDT Thu Aug 20 2026

The extended period will see a much needed return to a more typical summertime pattern. An upper level ridge will remain anchored over the western US while the eastern US will remain under the influence of a mid-level trough set up across most of the Eastern Seaboard through at least early next week. Expect mainly diurnally driven sea- breeze convection each day with seasonable PoPs (40-60%) favoring the afternoon and early evening hours, and then widely scattered coastal showers during the overnight period. Highest rain chances and most widespread coverage is expected across interior South Florida where the sea breezes and outflow boundaries collide.

Temperatures will remain above normal through the weekend and into early next week. Max heat indices will remain around advisory criteria each day, so additional heat headlines will remain possible.

AVIATION

(12Z TAFS) Issued at 733 AM EDT Thu Aug 20 2026

Generally calm conditions today with potential for thunderstorms in the afternoon over the eastern metro area. L/V winds until sea breeze circulations kick in between 16-18Z. SHRA-TSRA may result in erratic winds and reduced vis/cig at impacted terminals. Short fused amendments and TEMPOs may be needed in future TAF forecasts based on trends.

MARINE

Issued at 109 AM EDT Thu Aug 20 2026

Gentle west-northwest winds expected across the Gulf waters today with southerly winds across the Atlantic. These winds are expected to shift a little more southwesterly for the Gulf and southeasterly for the Atlantic on Friday. Seas will remain at 1-2 feet or less. Scattered showers and thunderstorms are possible late each day and in the late night hours which may result in locally hazardous winds and seas.

PRELIMINARY POINT TEMPS/POPS

Miami 93 81 93 80 / 50 20 40 10 West Kendall 93 78 92 78 / 60 20 30 10 Opa-Locka 94 81 94 79 / 50 20 40 10 Homestead 93 79 92 79 / 40 10 20 0 Fort Lauderdale 93 81 92 80 / 50 20 40 10 N Ft Lauderdale 93 81 93 80 / 60 10 40 10 Pembroke Pines 93 81 93 80 / 60 20 40 10 West Palm Beach 94 79 93 78 / 50 10 50 10 Boca Raton 92 80 92 79 / 60 10 40 10 Naples 92 79 91 79 / 20 30 30 20

MFL WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from 11 AM this morning to 6 PM EDT this evening for FLZ063-066>075-168-172>174.

AM...None. GM...None.