textproduct: Miami - South Florida

KEY MESSAGES

Updated at 630 PM EDT Tue Aug 18 2026 - Record heat possible today and Wednesday. A Heat Advisory is in effect for all of South FL today with heat indices of 105-112 expected.

- Unseasonably low RH values are expected over interior South FL today which may result in an elevated fire risk.

- Moderate risk of rip currents today for Collier county beaches.

UPDATE

Issued at 346 PM EDT Tue Aug 18 2026

No significant updates are needed to the current forecast package, as dangerous heat remains the main story for this afternoon. Well above normal temperatures have been recorded this afternoon across most of South Florida. Minimum temperatures are also expected to remain above normal tonight across coastal and metro areas, providing little relief. A relatively moist air mass will overspread the region on Wednesday, with PWATs forecast to increase to 1.6-1.9 inches. This will allow for an uptick in rain chances along mesoscale boundaries, with convective evolution heavily depending on how far the Atlantic sea breeze is able to push inland against the prevailing westerly flow. While increasing cloud cover should help keep ambient temperatures from climbing quite as high as today, increasing low-level moisture will support higher heat indices. Thus, Moderate HeatRisk will persist across a good portion of South Florida on Wednesday, with Major HeatRisk expected across most urban areas. Continue to practice heat safety by staying hydrated, taking frequent breaks in the shade or indoors, and checking on vulnerable individuals.

SHORT TERM

(Today through Wednesday) Issued at 105 AM EDT Tue Aug 18 2026

So you're telling me there's a chance! More on that later...

Record breaking heat is likely across much of South FL today, especially the east coast metro. Surface high pressure remains in control with upper level ridging across the region. In addition, Saharan dust will remain across South FL today. A frontal boundary will slide south from the TN Valley towards the SE US coast by late in the day. This will help push some moisture down the peninsula which may touch off some late day thunderstorms around the lake region. Otherwise, the rest of the area will be hot and dry again today. The east coast sea-breeze will struggle to make much of a push inland today, so westerly flow will be observed over much of South FL. This will allow temps to soar well into the 90s again this afternoon, with high temps in the low to mid 90s along the Collier coast, to upper 90s over the rest of South FL. Record high temps are highly likely today at MIA/FLL/DJT. Heat indices will easily get to 105-112 this afternoon, so another Heat Advisory will be in place from 11 AM to 7 PM.

Now to explain the first sentence above: Miami has only reached 100 degrees once, on July 21st 1942. The high temp today should easily reach the mid to upper 90s. According to the latest NBM probs, the Miami Airport has roughly a 10 percent chance of reaching 100 degrees today. So it's going to be very close...there is a chance!

On Wednesday, upper level ridging starts to weaken across the region as a trough starts to build into the eastern US. A mid and upper level weak low will also develop over the northeastern Gulf. The higher Saharan dust concentrations will finally get shunted to our south, and low level moisture will increase across the area. For the first time in awhile, seasonably normal PoPs (50-70%) will return to the forecast with scattered thunderstorms expected during the afternoon and early evening hours. Will need to watch the east coast sea breeze as it will likely become pinned across the metro. This may result in a few instances of urban and poor drainage flooding, especially if multiple storms pass over the same area. High temps on Wednesday will again approach records, with mid to upper 90s expected. Additional heat headlines will likely be needed as max heat indices again climb to 105-110.

LONG TERM

(Wednesday night through Monday) Issued at 105 AM EDT Tue Aug 18 2026

The upper level trough will become entrenched over the eastern half of the US through the rest of the week and through the upcoming weekend. The weak mid/upper level low may also meander in the northeastern Gulf through the end of the week. Overall, a more typical summertime pattern will be in place for South FL with diurnally driven thunderstorms during the afternoon and early evening hours, and isolated coastal showers overnight.

Temperatures will remain above normal through the extended period. Heat indices are likely to continue approaching Advisory criteria each day, so additional heat headlines will remain possible throughout the rest of the week and into the weekend.

AVIATION

(00Z TAFS) Issued at 630 PM EDT Tue Aug 18 2026

Mainly VFR conditions prevailing through the forecast period. L/V winds overnight across all terminals will increase out of the west after 14Z. Along the east coast terminals, winds are expected to shift SSE between 18-20Z as the Atlantic sea breeze pushes inland. Scattered showers and thunderstorms are possible along the sea breeze boundary, through confidence regarding impacts at east coast terminals remains low.

MARINE

Issued at 105 AM EDT Tue Aug 18 2026

Moderate to fresh westerly winds are expected today across the Gulf waters, with moderate southerly winds across the Atlantic. Seas generally 2 ft or less today.

BEACHES

Issued at 105 AM EDT Tue Aug 18 2026

A moderate onshore flow will result in an elevated risk of rip currents today for Collier county beaches.

FIRE WEATHER

Issued at 105 AM EDT Tue Aug 18 2026

Hot and mostly dry weather is expected to continue today. Min RH values over the southern Everglades will fall into the mid to upper 30 percent range this afternoon, with RH values in the 40-45 percent range over the rest of interior South FL. Given the unseasonably low RH values and ongoing drought conditions, there will be an elevated fire risk today.

CLIMATE

Issued at 105 AM EDT Tue Aug 18 2026

Record high temperatures are possible today and Wednesday. Here are the current records for Tuesday and Wednesday:

TUE(YEAR) WED(YEAR)

MIA 96 (2022) 96 (1909) FLL 98 (1921) 97 (1952) DJT 96 (2022) 97 (1938)

PRELIMINARY POINT TEMPS/POPS

Miami 80 97 81 94 / 0 40 30 60 West Kendall 77 97 78 94 / 0 40 30 60 Opa-Locka 80 97 81 95 / 10 40 40 60 Homestead 77 96 79 93 / 0 20 20 50 Fort Lauderdale 80 95 81 93 / 10 40 30 50 N Ft Lauderdale 80 96 81 94 / 10 50 30 60 Pembroke Pines 80 97 81 94 / 10 40 40 60 West Palm Beach 79 96 79 94 / 10 50 20 60 Boca Raton 79 94 79 93 / 10 50 30 60 Naples 80 92 79 92 / 0 20 30 40

MFL WATCHES/WARNINGS/ADVISORIES

FL...Heat Advisory until 7 PM EDT this evening for FLZ063-066>075-168- 172>174.

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