textproduct: Key West

KEY MESSAGES

- There is a marginal risk for excessive rainfall through Thursday morning as tropical moisture propagates across the area over the next couple of days. - Drier air associated with a cold front will arrive late this week and into the weekend, limiting the risk of excessive rainfall, though some rain chances will linger.

- Increasing northeasterly swell in the wake of the cold front will allow seas to build up to 5 feet by the end of the week and into the weekend, especially in the easternmost Straits of Florida.

DISCUSSION

Issued at 454 AM EDT Wed Sep 23 2026

The radar remains active across the Florida Keys and surrounding waters early this morning. A persistent zone of cyclonic flow remains in place over the region associated with low to mid-level troughing which is extended from the western Atlantic into the eastern Gulf towards the Yucatan Peninsula. In the upper-levels, a longwave trough is extending south from a low over the Great Lakes region all the way to the Yucatan, placing the Keys within a favorable zone for lift. The combination of these features in addition to a high influx of tropical moisture over the area will continue to promote scattered to numerous showers and occasional thunderstorms across the Florida Keys today. Showers/storms will be highly efficient rain producers, easily capable of 2-3" per hour rain rates. In addition, as we approach the upcoming full moon, high tides will peak above normal and the Coastal Flood Statement remains in effect through this afternoon. The main concern is that these two issues could compound to result in rapid instances of localized flooding along the Keys, particularly in poor drainage areas during high tide.

Meanwhile, a stalled surface front along the Gulf coast will be forced to the south Wednesday night and Thursday as the mid to upper-level trough shifts eastward towards the Mid-Atlantic region while stubborn deep-layer ridging remains parked over the ArkLaTex. This orientation is expected to culminate into the arrival of the first cold front of the season by the end of the week. This should initially maintain above normal rain chances until dry mid-level air advects south across the area by early this weekend, dropping rain chances to a seasonable level on Saturday. At this time, it's uncertain how far south the front will progress before eventually stalling, but current projections place the east to west oriented boundary across the Florida Straits by Sunday with deep west to northwesterly flow developing over the area. If the front were to stall further north than expected, it's likely that PoPs would remain elevated. Regardless, we're not expecting much of a noticeable temperature change with the frontal passage, but if we're lucky, afternoon dewpoints could briefly dip into the lower 70s, perhaps upper 60s in spots, along the Island Chain on Saturday. This will be short-lived however, as the front lifts back to the north early next week allowing for a resurgence in high moisture content across the area as a subsequent mid to upper level trough axis amplifies over the Deep South into the Gulf.

MARINE

Issued at 454 AM EDT Wed Sep 23 2026

Active weather remains present across the Keys waters early this morning resulting from deep-layer troughing centered over the eastern Gulf and Florida Peninsula. This is promoting light to gentle, occasionally moderate, southeasterly breezes. Winds will shift to the southwest by this afternoon as the surface trough begins to shift to the east of the Keys. Expect bouts of showers and thunderstorms to continue today with locally hazardous conditions in and near thunderstorm activity. Breezes will generally slacken through the later half of the week in advance of a cold front. Thereafter, expect freshening northerly breezes behind a frontal passage by Friday.

AVIATION

(06Z TAFS) Issued at 454 AM EDT Wed Sep 23 2026

SHRA will continue to propagate near and across the terminals this morning resulting from deep tropical moisture and troughing over the area. Expect occasional sub-VFR conditions through the morning hours with a potential lull by midday. TS chances or lower today, but may increase by mid to late afternoon in which a PROB30 was added. 5 to 10 knots southeasterly winds will gradually shift to the southwest to west throughout the day as the surface ridge axis shifts to the east of the Keys.

KEY WATCHES/WARNINGS/ADVISORIES

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