textproduct: Key West

KEY MESSAGES

- Increasing shower and thunderstorm chances expected through the week, peaking tonight through Thursday.

- Light to gentle east to southeast breezes expected this morning, becoming gentle for this afternoon and tonight, except becoming gentle to moderate for the Straits of Florida tonight.

DISCUSSION

Issued at 1004 AM EDT Tue Aug 25 2026

An MCV west of Andros Island continues to produce scattered thunderstorms just to the east of our waters this morning. Earlier shower and thunderstorm activity in the distant Straits produced an outflow boundary that moved north across the Upper Keys and into the Florida Bay, with associated winds measuring 30 knots at Carysfort Reef Light. While 1.49" PWATs were measured on the 12Z KKEY RAOB, MIMIC-TPW imagery shows a plume of much higher PWATs advecting towards the Florida Keys from the southeast. This will be the primary source of our enhanced rain chances today, but moreso overnight and into the rest of the week with guidance suggesting that tropospheric moisture will become much higher than it has been lately. Thunderstorm potential this afternoon will be largely influenced by the number of outflow boundaries evident on visible satellite imagery, especially on the northern side of the island chain and in the southeastern Gulf. Temperatures are currently in the mid 80s near Marathon due to an earlier shower, but expect temperatures to easily warm to near 90 degrees along the island chain with dewpoints in the mid to upper 70s. Surface ridging extending across the area from the Atlantic high is promoting light to gentle southeasterly breezes which may become moderate at times tonight as the ridge builds further west and the pressure gradient increases.

MARINE

Issued at 1004 AM EDT Tue Aug 25 2026

Isolated thunderstorms are moving northwest across the Southeastern Gulf while showers and thunderstorms associated with a nearly stationary MCV are ongoing just outside of our waters to the east of the Florida Straits. Outflow boundaries from earlier thunderstorm activity did produce occasional gusts of 20-30 knots along the Hawk Channel and Florida Bay, but general flow consists of light to gentle southeasterly breezes influenced by the expanding Atlantic ridge. From synopsis, the western periphery of an Atlantic high is expected to maintain control of the Keys for the next several days. This will promote peaking and lulling east to southeast breezes. Breezes will peak in the evening through early morning and lull in the afternoons. The strongest surge of breezes is anticipated to be Wednesday night where mostly moderate breezes are expected throughout the Florida Keys coastal waters.

AVIATION

(15Z TAFS) Issued at 1004 AM EDT Tue Aug 25 2026

The majority of this TAF period will feature VFR conditions at both terminals, but there may be an occasional shower which would necessitate a TEMPO due to reduced visibility and erratic wind gusts. With surface ridging extended across the Keys, surface winds will be southeasterly at 5 to 10 kts with a scattered low- level cumulus deck across the area.

FORECAST

The pattern for the next several days can be summed up with the western periphery of Atlantic ridging remaining over the Keys along with bouts of moisture and embedded subtle upper level shortwaves traversing through. As moisture continues to round the western side of the high, rain chances will gradually increase through the week. Peak rain chances are expected tonight through Thursday at 50%. In addition, east to southeast breezes will peak in the evenings and overnight and lull in the afternoons.

The interesting time frame still looks to be late week into the weekend when a stronger shortwave presses through the Keys. For now, rain chances decrease slightly for this time frame, though, there is the chance that these will increase in the coming days. Therefore, late week is potentially setting up to be the bigger show as we will have basically all the ingredients lined up for robust convection. We will have the instability, moisture, and lift all lining up at the same time. More simply put, expect a more unsettled weather pattern for the foreseeable future which is entirely normal for this time of the year. Average rain chances peak for the month of September, which is only a week away. It is also hard to pinpoint exact timing for convection as basically just expect rounds of showers and thunderstorms are anticipated for the next several days. In addition, expect daytime highs near 90 degrees with overnight lows in the lower to mid 80s and dew points in the mid to upper 70s. Of course, temperatures may fall into the upper 70s where any showers and storms move over.

TROPICS: The National Hurricane Center (NHC) continues to monitor 2 areas across the Atlantic Ocean with none of these systems currently posing a threat to the Keys. The area across the Eastern Tropical Atlantic now has a 60% percent or medium chance of developing through 48 hours and a 70% percent or high chance of development through the next 7 days.

PRELIMINARY POINT TEMPS/POPS

Key West 90 83 90 83 / 20 50 50 40 Marathon 90 82 90 82 / 30 50 50 50

KEY WATCHES/WARNINGS/ADVISORIES

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