textproduct: Key West

KEY MESSAGES

- A moisture surge will support 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.

DISCUSSION

Issued at 1021 PM EDT Fri Sep 4 2026

Significant changes have not been needed to the forecast this evening. We're currently in a lull as far as shower/thunderstorm activity goes despite the high 2.12" PWATs and lack of inhibition that was measured on the 00Z KKEY RAOB this evening. IR satellite imagery does show a growing cu field near the Middle to Upper Keys, so we may begin to see redevelopment here shortly. Broad ridging continues to dominate the pattern, centered over the Lower Mississippi River Valley but extending into the Western Atlantic. It will become somewhat suppressed by longwave troughing over the Northeast CONUS over the next 24 hours, but for now, CIMSS steering products depict the axis of a shortwave ridge centered over the Bahamas. This is likely suppressing activity across the area. As the longwave trough deepens over the Eastern Seaboard, weak height falls are forecast to occur during the day tomorrow, somewhat loosening the grip of the expansive ridge, and hi-res models continue to support Chance PoPs across the area. Its quite a muggy night out there with current temperature readings in the mid 80s and dewpoints in the upper 70s. Highs in the 90s are expected tomorrow with heat indices ranging from 100-105 degrees. Make sure to stay hydrated out there this weekend!

MARINE

Issued at 1021 PM EDT Fri Sep 4 2026

No watches, warnings, or advisories are currently in effect for the Florida Keys waters. However, scattered thunderstorms will occasionally push through the marine zones through the weekend. The primary threat for any storm will be dangerous cloud to surface lightning strikes.

From synopsis, the western periphery of a weak North Atlantic high will remain in loose control of the Keys coastal waters for the next few days. Light to gentle, occasionally moderate, east to southeast breezes overnight through morning will become light and variable at times during the afternoon and evenings. In addition, the overall flow will keep low-level moisture in place across the region, with seasonally normal rain and thunder chances.

AVIATION

(00Z TAFS) Issued at 1021 PM EDT Fri Sep 4 2026

Convection has dwindled this evening, and VFR conditions are expected to continue at both terminals for much of the night. Redevelopment is expected to occur during the morning hours due to ample amounts of low-level moisture present across the area. Introduced a PROB30 for TSRA from 12-16Z at both sites. TEMPOs may be introduced in later TAF issuances as confidence in timing improves.

KEY WATCHES/WARNINGS/ADVISORIES

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