textproduct: Miami - South Florida

KEY MESSAGES

Updated at 106 PM EDT Wed Sep 9 2026

- Numerous showers and thunderstorms will develop today, focusing across the western half of the peninsula this PM. Gusty winds and dangerous cloud to ground lightning is possible with any storm. - Slow moving storms will increase the risk for localized flooding especially if rainfall occurs in a short period of time across urban southwestern Florida. - High temperatures will generally rise into the low to mid 90s across most of South Florida through this week, creating widespread Moderate to Major HeatRisk each day.

SHORT TERM

(Today through Thursday) Issued at 204 AM EDT Wed Sep 9 2026

The hallmarks of an expansive and anomalous middle to upper level ridge across the majority of the southern United States is in full swing this morning as observed isoheights and 500mb temperatures across our region and much of the southern CONUS indicate a continued strengthening of deep layer ridging. Forecast HREF 500mb heights for the remainder of today across the majority of the southeastern United States as well as South Florida are between the 99th-100th percentile for this time of year, indicative of just how strong the ridge is compared to the climatological mean. With such a robust ridge aloft, 500mb temperatures (-2C to -3C in spots to our north) across most of the southeastern United States are nearing the 100th percentile for today's date. Closer to home across South Florida (and on the periphery of the expansive ridge), 500mb temperatures will be closer to the 75th percentile for today's date in the -5C to -6C range. 300mb and 500mb flow will in turn become easterly in nature today as anticyclonic flow enhances around the expansive ridge axis to our north. Closer to the surface (700mb, 850mb, 925mb), background flow will become southeasterly to easterly in nature as a large and expansive area of surface ridging will also begin to build across the western Atlantic waters and across the Florida Peninsula. With deep layer easterly flow in play across the region today, a typical wet season regime is in the forecast once again after a prolonged reprieve. Overnight and morning convection will favor the east coast of South Florida before the Atlantic sea- breeze and outflow boundaries push the foci of convection further westward across the peninsula as the day progresses.

The confluence of a land breeze from earlier diurnal convection and light easterly to southeasterly flow over the nearshore Atlantic waters may set the stage for early morning shower and thunderstorm activity across the instability laden Gulfstream waters over the next several hours. With the aforementioned easterly wind component now in play, early morning showers and thunderstorms may briefly move onshore along the east coast of South Florida before a stable atmosphere results in the waning and dissipation of activity further inland. Diurnal heating and the erosion of a stout near surface inversion (and any residual convective inhibition) will give way to widespread cumulus development across most of the peninsula during the late morning and early afternoon hours before easterly background flow focuses the bulk of diurnal convective activity across the western half of the peninsula. Once again, ample instability (forecasted CAPE of 3000-4000+ J/kg) and moisture will lead to scattered to numerous shower and thunderstorms this afternoon and evening. However with the lack of synoptic forcing, the threat of strong/ severe convection remains minimal as temperatures remain warm aloft and low to mid level lapse rates remain rather lackluster and unassuming. Frequent lightning, gusty sub-severe winds, and heavy rainfall remains the primary hazard with showers and thunderstorms today. With a saturated environment and light easterly flow (Corfidi upshear and downshear vectors below 10 knots) in the vertical column, pockets of heavy rainfall are once again possible today, especially when convection is pinned along boundary collisions. HREF's LPMM depicts isolated pockets of 2-3+" of rainfall primarily across a pinned Gulf breeze. If these values were to occur directly over portions of the Naples metro, isolated urban flooding will be possible. To account for this potential, a targeted marginal ERO (excessive risk of rainfall) has been coordinated with the Weather Prediction Center for urban southwestern Florida today.

High temperatures are forecast to peak in the low to mid 90s this afternoon before convection (and resultant cloud debris) act to cool temperatures down at impacted locales. Before any relief from the heat, ample humidity and sunshine will result in apparent temperatures in the 100F to 105F degree range across most of the region with peak apparent temperature values closer to 106-107F across southwestern Florida where the onset of convection may be delayed. NWS's Probabilistic HeatRisk has high probabilities (80- 100%) of Moderate HeatRisk and low to moderate probabilities (20- 40%) of Major HeatRisk for the majority of urban areas across South Florida today. Be sure to take necessary heat precautions today if you or your loved ones are sensitive to heat.

Diurnal convection will once again wane in areal coverage after sunset this evening with the loss of surface heating. A saturated low level boundary layer and ample instability offshore will once again support the potential of nocturnal convection across the nearshore Atlantic waters and immediate east coast of South Florida late tonight into early Thursday morning. Continued southeasterly flow across South Florida in response to the surface ridge axis across the western Atlantic waters will keep the standard easterly flow regime in place on Thursday with activity gradually propagating on a spatial and temporal scale from east to west as the day progresses. Aloft, middle to upper level ridging will begin to bifurcate with the more pronounced mid-level ridge axis shifting into the western Atlantic waters and a secondary mid-level ridge axis developing across the Gulf during this time frame. In response, 500mb flow will veer slightly more southerly during this time frame which may focus more convection across the Lake Okeechobee region as well as southwestern Florida on Thursday afternoon and evening. Some guidance also hints at a mid-level impulse lifting northwards across the region during this time period which may act to cool 500mb temperatures near or just below (-6C to -7C) the climatological mean, steepen low to mid level lapse rates, and enhance convection to become more widespread in nature on Thursday. Closer to the surface, a modeled moisture surge of deep moisture associated with a weak perturbation (perhaps a weak trough axis) is also forecast to arrive across the region which may also act to enhance convection. Forecast soundings and NASA's Dust Extinction Aerosol Optical Thickness Model also depict the initial arrival of a very diffuse plume of Saharan Dust on Thursday which could also act as a limiting factor for convective growth. For the time being however, overnight mesoscale models do not suggest that dust concentrations will be sufficient enough to have any impact in suppressing coverage on Thursday. Convective hazards on Thursday afternoon will be similar to what is forecast for today: heavy rainfall & localized urban flooding, frequent lightning, and gusty sub severe winds being the primary threats of concern.

With a rinse and repeat pattern ongoing, a quick warm up is forecast on Thursday before convective initiation. High temperatures are forecast to top out in the low to mid 90s once again with peak apparent temperatures once again in the 100F-105F range across the eastern half of South Florida and closer to 106-107F across southwestern Florida. NWS's Probabilistic HeatRisk once again depicts high probabilities (70-90%) of Moderate HeatRisk and low to moderate probabilities (30-50%) of Major HeatRisk for the majority of urban areas across South Florida on Thursday.

LONG TERM

(Thursday night through Tuesday) Issued at 204 AM EDT Wed Sep 9 2026

South Florida will remain situated between split upper-level high pressure over the western Atlantic and the Gulf, before ridging re- establishes across the eastern CONUS early next week. At the surface, high pressure over the western Atlantic will maintain a light easterly flow regime across the peninsula through the forecast period. Overall, a typical wet season pattern is expected to continue, with early morning showers and isolated storms developing along the East Coast before activity gradually shifts inland, peaking across inland and SW Florida each afternoon.

Bouts of drier air will attempt to filter into the region through the weekend as a Saharan dust plume approaches the region, with the highest concentrations expected to arrive early next week. While the core of the dust plume is forecast to remain south of the peninsula, mid-level dry air intrusion at its periphery could steepen lapse rates and increase DCAPE locally, enhancing the threat for severe wind gusts within robust afternoon convection. Conversely, greater concentrations of Saharan dust overspreading the region could act to suppress overall convective activity to some degree. Guidance continues to suggest that PWATs will remain close to slightly above climatology through the forecast period, indicating that sufficient moisture will be available to support at least scattered daily convection through the long term. Outside of any influence from the Saharan dust plume, the potential for severe weather is expected to remain fairly limited, with wind shear staying weak and 500 mb temperatures forecast to remain near to slightly warmer than climatology. Given the uncertainty regarding the exact timing and extent of the dry air intrusion, trends will continue to be monitored.

High temperatures will rise into the lower 90s across most areas through early next week, reaching the mid 90s over interior SW Florida. Overnight lows will range from the low 70s across the interior to the low 80s along the coasts. Major HeatRisk probabilities increase into the weekend as onshore flow maintains elevated heat indices and limits overnight cooling, then decrease early next week as drier air arrives.

AVIATION

(18Z TAFS) Issued at 106 PM EDT Wed Sep 9 2026

SE winds around 10 kts this afternoon except for APF which will have a westerly Gulf breeze. Scattered thunderstorms this afternoon into early evening may result in brief flight restrictions and erratic winds. VCSH after 08Z tomorrow morning along the east coast terminals.

MARINE

Issued at 204 AM EDT Wed Sep 9 2026

Gentle to moderate easterly to southeasterly winds will prevail across the local waters of South Florida for the remainder of the work week. The exception to this will be a brief period each afternoon across the nearshore Gulf waters as surface winds become more southerly in direction due to the gulf sea breeze circulation. Scattered to numerous showers and thunderstorms will develop over the local waters both during the day and overnight periods. Gusty and erratic winds, along with brief periods of rough seas, will be possible in and around any thunderstorm activity. Wave heights across the Atlantic waters will increase to 3-4 feet by this afternoon as northeasterly swell arrives across the region and interacts with the Gulfstream current. Seas across the nearshore Gulf waters will remain below 2 feet for the remainder of the work week with wave heights also subsiding across the nearshore Atlantic waters later in the week.

BEACHES

Issued at 204 AM EDT Wed Sep 9 2026

The combination of increasing northeasterly swell and onshore surface winds is forecast to result in an elevated rip current risk at Palm Beach County beaches beginning this afternoon.

PRELIMINARY POINT TEMPS/POPS

Miami 81 90 81 90 / 40 60 20 60 West Kendall 79 90 79 90 / 40 70 10 70 Opa-Locka 79 90 80 90 / 40 60 20 70 Homestead 79 91 80 91 / 50 70 20 60 Fort Lauderdale 80 90 81 90 / 40 50 20 60 N Ft Lauderdale 81 91 80 91 / 40 60 20 70 Pembroke Pines 80 90 79 90 / 40 60 20 70 West Palm Beach 79 91 78 91 / 30 70 20 70 Boca Raton 80 90 80 90 / 30 60 20 70 Naples 76 91 77 90 / 30 70 30 80

MFL WATCHES/WARNINGS/ADVISORIES

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