textproduct: Key West

KEY MESSAGES

- A moisture surge will support bouts of elevated rain and thunder chances through the Labor Day holiday weekend.

- The primary threat for any stronger thunderstorms will be dangerous lightning strikes. When thunder roars, go indoors. If on a boat, stay low, or go below.

- Heat indices will approach the mid 100s daily, with little relief in the muggy conditions overnight. Know the signs of heat stress, take frequent breaks, and stay hydrated.

AVIATION

(18Z TAFS) Issued at 155 PM EDT Sat Sep 5 2026 VFR conditions will prevail through most of the evening hours. A wave of modestly drier air should suppress most vicinity showers through at least 06z this evening. Thereafter, additional activity may develop. Confidence is too low to include explicit mention of potential impacts to the terminals at this time, although this will be reevaluated for the 00z TAF issuance. Near-surface winds will go variable this evening, gradually resuming a southeasterly direct overnight through 18z Sunday.

PREV DISCUSSION

Issued at 1105 AM EDT Sat Sep 5 2026 Low-level geopotential height and wind analysis depicts a departing inverted trough approaching the central Gulf, a second inverted trough approaching the eastern Bahamas, and a surface high pressure system extending across much of the North Atlantic. The sum of these features supports generally light southeast to south surface winds. The 12z morning sounding sampled at KEY highlighted deep tropical moisture, along with unidirectional southeasterly mean steering flow at around 10 knots. KBYX radar has been fairly active all morning, depicting scattered showers with a few speckled embedded thunderstorms, mainly across the Lower Keys and to the northwest. This is where CIMSS total precipitable water product highlights the best tropospheric- integrated moisture, largely associated with the eastern flank of the aforementioned departing easterly wave.

For the balance of today, expecting the heaviest convective activity to be within the next several hours, before an undulation of drier air works towards the CWA. The wave of drier air will be short-lived, with a batch of moist air trailing this feature across the Bahamas, making its way to the Keys late tonight through Sunday. The inherited forecast calls for mid- level rain and thunder chances today, and given radar trends, this seems quite plausible, mainly across the Lower and Middle Keys. No changes proposed.

MARINE

Issued at 1105 AM EDT Sat Sep 5 2026 No watches, warnings, or advisories are currently in effect for the Florida Keys. From synopsis, Light to gentle southeast breezes will prevail through mid week as weak steering flow persists across the region, thereafter breezes will freshen to gentle to moderate as high pressure builds in. Waves of low- level moisture pushing across the Keys will support elevated rain and thunder chances through Sunday, possibly returning to near normal by mid week.

KEY WATCHES/WARNINGS/ADVISORIES

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