textproduct: Key West

KEY MESSAGES

- Near normal rain chances in the short term is expected to give way to considerably higher rain chances later in the work week.

- Winds are expected to trend upwards over the next several days, likely peaking in the moderate to fresh range around mid week.

- Heat index values will range from 100-108 degrees daily, with little relief from the muggy conditions overnight. Know the signs of heat stress, take frequent breaks, and stay hydrated.

DISCUSSION

Issued at 400 AM EDT Mon Sep 14 2026

A mid latitude trough aligned along the Atlantic coast is holding an Atlantic ridge at bay, off to our east. As a result, the local pressure gradient is sloppy and resulting in light generally east to southeasterly breezes. Meanwhile, weak lower to mid level ridging spans the Florida Peninsula. While last evenings sounding indicated modest CAPE with high precipitable water around the 90th percentile at 2.21 inches, there was a hint of lower level inhibition. Much of this lower level inhibition was likely caused by a gulf outflow boundary that swept through our area this evening. That said, shower activity across the Keys has been nearly absent over the past several hours.

The local pressure gradient will remain poorly defined today with a split ridge across Florida. As a result, while surface winds will try to be light out of the east to southeast, a large portion of our forecast area will likely become variable and dominated by mainland daytime heating effects. Forecast soundings indicate weak low level inhibition will persist, along with modest CAPE. Rain chances are expected to be near normal, but highlight the potential for mainland seabreeze activity to roll southward into the Upper Keys later this afternoon and evening. No trend in temperatures are expected and highs will remain near 90, lows in the lower 80s, and dew points in the mid to upper 70s.

Over the following few days, a robust continental high cell will spread southward through the eastern United States as the mid latitude trough pushes out into the Atlantic. This high will gradually bolster the local pressure gradient and northeast to easterly breezes will steadily freshen through this period. Expect winds to peak in the moderate to possibly fresh range late Tuesday into late Wednesday. The precipitation story is complicated as the tail end of the mid latitude upper trough is expected to pinch off east of the mid Atlantic Coast and interact and absorb a TUTT cell near Hispaniola. This will setup a broad trough off to our east. All this is then expected to advance westward through Florida and the Keys. Consequently, deep layered moisture is expected to climb sharply through the mid and latter part of the week. This along with falling mid level heights due to the retrograding deep layered low complex should point towards increasing PoPs. For now will mostly retain the currently advertised increasing trend in PoPs for the week.

MARINE

Issued at 400 AM EDT Mon Sep 14 2026

A mid latitude trough swinging off the Atlantic coast will keep an Atlantic pressure ridge well off to the east. This will result in a nebulous pressure field across Keys waters today. Winds be light, tending broadly northeast to southeasterly, however expect variability through the day. An expansive continental high pressure system will build southward down the eastern United States over the next few days resulting in freshening northeast to easterly breezes. Winds are expected to peak in the late Tuesday through late Wednesday time frame. While not expected, marine cautions cannot be ruled out.

AVIATION

(00Z TAFS) Issued at 400 AM EDT Mon Sep 14 2026

VFR conditions will prevail at the island terminals today. Shower and thunderstorm chances are expected to be near normal today. Surface winds will be light and variable, tending broadly northeast to southeasterly.

PRELIMINARY POINT TEMPS/POPS

Key West 91 82 92 81 / 30 30 30 50 Marathon 90 82 90 82 / 30 30 40 50

KEY WATCHES/WARNINGS/ADVISORIES

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