textproduct: Miami - South Florida

KEY MESSAGES

Updated at 722 AM EDT Thu Jun 18 2026

- Heat Advisory in effect from 12-7 PM today for all of South Florida. Heat indices as high as 110 degrees expected.

- Scattered thunderstorms are expected this afternoon into early evening across interior South Florida. Heavy rainfall may result in localized urban and poor drainage flooding.

- Smoke from wildfire activity in central Miami-Dade county will continue to disperse across much of the region. Lower air quality from wildfire smoke can be hazardous to sensitive populations.

SHORT TERM

(Today through Friday) Issued at 314 AM EDT Thu Jun 18 2026

The subtropical high pressure in the Atlantic is expected to shift closer to the far western Atlantic today while the remnants of what was Tropical Storm Arthur begin to advect across the Deep South. As this slight pattern shift occurs, low level flow will stay rather light as the tighter pressure gradient will slide off further north where Arthur's remnants advance. As a result, convection today is expected to be limited and focused in the interior regions as the main lifting mechanism will be the sea breeze circulations along both coasts, and these boundaries will be able to move further inland under a weak flow pattern. Rain chances are capped at 40-50% even in the interior because of a weak layer of Saharan Dust (SAL) creating a dry pocket. With that said, enough instability and moisture exists along with model soundings depicting an inverted-V signature, which could support the possibility of a pulse-severe storm or near severe storm. However, this will be a highly conditional case with very low-end chances of occurrence.

On Friday, rain chances will increase with scattered to numerous showers and thunderstorms expected as a shortwave trough detaches from Arthur's remnants and shifts southwards towards our region as the ridge of high pressure gets broken down. Positive vorticity advection impulses will create a more unstable environment that will be able to take advantage of the deep moisture in place (PWATs of 1.8-2.2" or more). Additional convection will occur as a result of the daily sea breezes and thunderstorm outflow boundary collisions. Therefore, PoPs for Friday rise to 60-80% across inland South Florida and 50-60% for coastal metro areas. PoPs do trend higher towards the east coast metro versus the Gulf coast since steering flow will be out of the west-southwest. Once again, conditions could be suitable for a pulse-severe environment on Friday, but the primary hazards will be heavy downpours and gusty winds. The strongest storms could also produce areas of localized flooding.

Heat will continue to be a topic of concern as well as we end the week. As this weak flow pattern sets up and Arthur's remnants advect eastward, near-surface flow should shift more southeasterly but will still be on the lighter side. Thus, sea breeze dominance from the warm waters can lead to elevated dew points in the upper 70s for most zones, which with high temperatures reaching the mid 90s is expected to cause heat index values to rise to 105-110F. Therefore, have issued a Heat Advisory again today but this time expanding to more zones. Today, the advisory has been issued for all counties and zones. More heat headlines are likely to be needed heading into Friday and this weekend.

LONG TERM

(Friday night through Wednesday) Issued at 314 AM EDT Thu Jun 18 2026

The disruption in the subtropical high pressure pattern will continue through this weekend and into next week with broad troughing encompassing the majority of the central U.S. and the Eastern Seaboard. Vorticity maxima will continue advecting across or in the vicinity of South Florida into next week as troughing across the country enhances under increased jet dynamics. Deep moisture will remain present each day with PWATs of 1.8-2.0+ inches and this will support scattered to numerous showers and thunderstorms each day through Monday. The most widespread activity is expected to occur over inland portions of South Florida as this where will be where the sea breezes collide.

Heading into the middle of next week and the end of this forecast period, a thicker Saharan Air Layer (SAL) will approach the region from the east. These SAL's contain very dry air especially in the mid-levels and upper levels of the atmosphere, which can inhibit deep convective growth and also minimize the widespread nature of showers and thunderstorms. Thus, rain chances decrease back to the 20-40% range for the middle of next week which will be down from 60- 80% in the days prior. There is no projected change in the overall flow pattern, so most of the showers and storms that do form will still be expected to form over the interior.

Heat will remain a concern in the extended period with daily high temperatures reaching the mid 90s for most areas. Some locations in the interior could see highs reach the upper 90s each day. Additionally, maximum heat index values will continue to reach the 105-110 degree range most days and may require ongoing headlines for heat.

AVIATION

(12Z TAFS) Issued at 722 AM EDT Thu Jun 18 2026

VFR conditions will prevail throughout the forecast period. Light winds this morning will increase out of the SE after 14z and will range between 10 to 15 kts through the afternoon hours. At KAPF, winds will increase out of the SSW during the late morning hours and will range between 10 to 15 kts this afternoon. Scattered showers and storms will develop over the interior areas this afternoon, however, they will not have any impacts around the terminals.

MARINE

Issued at 314 AM EDT Thu Jun 18 2026

Gentle to moderate southeasterly winds are expected for the end of the week across the Atlantic waters while the Gulf waters see winds shift to the west each afternoon. Scattered thunderstorms will are possible each day, which may result in locally hazardous winds and seas. Outside of storms, seas will be 1-2 ft or less across all local waters for the end of this week and into the weekend.

FIRE WEATHER

Issued at 314 AM EDT Thu Jun 18 2026

Multiple fires continue to burn in Miami-Dade county and may not get much assistance from rainfall today. Wind flow today is expected to shift more southeasterly while also lessening. Flow will remain southerly to southwesterly for Gulf coast areas, meaning that shower and thunderstorm coverage today will be focused across the interior portions of South Florida and away from both coasts. With flow shifting to a more southeasterly direction in Miami-Dade today, smoke is expected to disperse more to the northwest compared to the last two days and will continue to pose air quality issues. Maximum dispersion indices will be in the generally good category both today and tomorrow.

PRELIMINARY POINT TEMPS/POPS

Miami 93 80 93 79 / 10 0 30 20 West Kendall 94 79 94 77 / 10 0 30 20 Opa-Locka 94 80 94 79 / 10 0 30 20 Homestead 93 81 93 79 / 10 10 20 20 Fort Lauderdale 92 81 92 80 / 10 0 30 30 N Ft Lauderdale 91 80 92 79 / 10 0 40 30 Pembroke Pines 96 81 96 81 / 10 0 40 30 West Palm Beach 92 80 93 79 / 10 10 50 40 Boca Raton 91 81 92 80 / 10 0 40 30 Naples 92 80 92 79 / 10 10 20 10

MFL WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from noon today to 7 PM EDT this evening for FLZ063-066>075-168-172>174.

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