textproduct: Miami - South Florida

KEY MESSAGES

Updated at 727 AM EDT Wed Jun 17 2026

- A Heat Advisory is in effect today for coastal/metro Miami- Dade and Broward. Further heat concerns are expected for all of South FL through the end of the week.

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

- Smoke from wildfire activity in central Miami-Dade county is expected to drift northwards/northeastwards and could cause lower air quality that may be hazardous to sensitive populations.

SHORT TERM

(Today through Thursday) Issued at 240 AM EDT Wed Jun 17 2026

Broad troughing is depicted from the central U.S. stretching across through most of the Eastern Seaboard. The lone exception to this is the far southeast (including the Florida Peninsula) where surface high pressure is stretched from the central Atlantic into the eastern Gulf. Additionally, Potential Tropical Cyclone One (PTC 1) is positioned near the coast of Southeastern Texas and is expected to propagate northeastwards towards Louisiana. With the surface high pressure in the Atlantic and the associated mid-level ridge expected to linger across our region for the next few days, the progression of both PTC 1 and the broad trough to the north will help to determine the exact low level wind flow direction that will influence where the highest rain chances will be.

For today, near-surface flow should remain more southwesterly and steer the strongest convection towards Broward and Palm Beach counties again. However, initial convective initiation could begin in inland Miami-Dade before progressing northeastwards. Model soundings are again showing some mid-level dry air that may limit instability and there also appears to be some low amounts of Saharan Dust advecting into the area, but convergence along the sea breeze boundary and prevailing southwesterly flow still could be enough to spark a stronger core thunderstorm or two with a more robust updraft. This will be a highly conditional case with strong wind gusts being the primary hazard as DCAPE values in excess of 1000 J/kg are identified in many model soundings. Additional concerns will be for periods of heavy rainfall that may lead to localized flooding. HREF LPMM shows a potential high-end scenario of 2-4" in a short time duration of 1-2 hours. If this occurs over a vulnerable poor drainage area or metro location, flooding could arise. For Thursday, low-level to mid-level flow weakens rather largely and thus both the Atlantic and Gulf breezes will be able to advance inland to where they collide over the interior and produce the strongest storms of the day across inland South Florida.

Lastly, the risk for excessive heat remains ongoing into the end of this week. With dry air in the mid-levels helping to inhibit strong convective growth until later in the afternoon when peak heating is reached, it is viewed as a likely possibility that many locations across Miami-Dade and Broward counties could reach advisory levels of 105F for 2 hours or more consecutively. Therefore, have opted to issue a Heat Advisory again today from 12PM to 6PM for coastal and metro zones in the aforementioned counties with maximum heat indices of 105-108F possible. Leaving out the inland zones of these counties since rainfall is expected to diminish the heat potential earlier in the day. Additional confidence in this issuance was present from the Probabilistic HeatRisk prototype which shows a 60-80% chance of reaching Major HeatRisk (Level 3 of 4), which would affect any person who lacks proper cooling or hydration. It even gives a 10-20% chance of reaching Extreme HeatRisk (Level 4 of 4) and would pose an even greater chance for heat related illnesses.

General high temperatures today and tomorrow will be in the low to mid 90s with overnight lows Wednesday night. ranging from the low 70s near Lake Okeechobee to the upper 70s and low 80s near the coasts.

LONG TERM

(Thursday night through Tuesday) Issued at 240 AM EDT Wed Jun 17 2026

Surface high pressure in the western Atlantic will remain anchored over South Florida into Friday, although PTC 1 will be advecting eastwards as it starts to break down and lose steam. However, this progress of PTC 1 will attempt to weaken the ridge over South Florida while the energy of PTC 1 also gets absorbed into the broad upper level trough pattern across the eastern US. This could allow for the broad troughing axis to extend southwards into Central or even South Florida on Friday into this weekend. In response, positive vorticity advection is modeled to stream southwards and these impulses would be able to provide a lifting mechanism in addition to the daily sea breeze circulations and diurnal heating. In general, our convection will be primarily diurnally driven sea breeze convection each day with the highest PoPs favoring inland locations and western portions of the east coast metro as both the Atlantic sea breeze and Gulf breeze will be able to advance inland (mid-level and jet stream level winds at 20 kts or less). Additional storms are expected to fire up along outflow boundaries and their collisions. Overnights will be fairly quiet each night outside of some occasional coastal showers along the Atlantic coast. This unsettled pattern is expected to last into early next week with scattered to numerous showers and thunderstorms likely each day.

Temperatures during the extended period will remain above normal in the low to mid 90s each day with some areas in inland South Florida potentially reaching the upper 90s. Heat indices will likely approach advisory criteria each day, maxing out at 105-110 degrees. Timing of rainfall each day will be critical on whether or not advisory/warning criteria will be reached.

AVIATION

(12Z TAFS) Issued at 727 AM EDT Wed Jun 17 2026

Mainly VFR conditions will prevail throughout the forecast period. Light winds this morning will increase out of the SSE after 15z and will range between 10 to 15 kts through the afternoon across the east coast terminals. Scattered showers and storms will develop near the east coast terminals starting around 19z and could bring periods of MVFR or IFR later in the afternoon if a storm directly impacts the terminals. At KAPF, winds will increase out of the SW after 15z.

MARINE

Issued at 240 AM EDT Wed Jun 17 2026

Gentle to moderate southerly winds continue today and are expected to shift more southeasterly on Thursday. Scattered thunderstorms will continue to be possible each day, which may result in locally hazardous winds and seas at times. Outside of convection, seas will be 1-2 ft or less across all local waters.

FIRE WEATHER

Issued at 240 AM EDT Wed Jun 17 2026

A couple of different fires (Quarry 2 and Well Fire) continue to burn near the far western suburbs of metro Miami-Dade county where fire fighters continue to work on further containing the fires. Winds today will continue to be primarily out of the south to southwest, which will steer smoke to the north and northeast. There will be chances for some scattered shower and thunderstorm development near the fire locations in the afternoon and evening hours today with generally good to very good dispersions.

PRELIMINARY POINT TEMPS/POPS

Miami 93 80 93 80 / 40 10 10 0 West Kendall 94 79 94 79 / 40 10 20 0 Opa-Locka 95 80 94 80 / 40 10 20 0 Homestead 93 80 93 81 / 30 10 10 0 Fort Lauderdale 93 81 92 81 / 30 10 10 0 N Ft Lauderdale 93 80 92 80 / 40 20 20 0 Pembroke Pines 97 81 96 82 / 40 10 20 0 West Palm Beach 93 79 93 80 / 40 20 20 10 Boca Raton 92 81 92 81 / 40 20 20 10 Naples 92 81 92 80 / 0 10 20 10

MFL WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory from noon today to 6 PM EDT this evening for FLZ072-074-172-173.

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