textproduct: Key West

KEY MESSAGES

- Moderate to major saltwater flooding of low elevation streets and lots is likely to continue over the next few day or so due to King Tide. Don't drive through flooded roadways. Boaters can expect less clearance under fixed bridges.

- A Coastal Flood Warning is in effect for the Upper Keys, particularly along the sounds, bay side of Key Largo. A Coastal Flood Advisory is in effect for the Middle and Lower Keys.

- A wet pattern has developed this evening as deep tropical moisture is pumped northward across the Keys. This will maintain above normal rain and thunder chances, lingering over the next few days.

DISCUSSION

Issued at 925 PM EDT Mon Sep 28 2026

An old lower level front has lifted northward into the Keys this evening. While surface flow is rather weak, a lower level ridge axis is aligned across Cuba. This has set up a broad confluence zone across our area, between the ridge to the south and troughing over the eastern United States. In addition, upper level troughing continues to sharpen across the Gulf of America. Altogether, these factors has setup a wet pattern across the Keys. This evenings sounding indicated precipitable water has jumped considerably to 2.5 inches. Also, an earlier outflow boundary, emanating from activity near Cuba, swept northward across the Keys and bumped surface dew points up 5 degrees into the mid 70s. Despite the dew point rise, the outflow boundary likely held back convective proliferation nearer the island chain this evening. Scattered to numerous shower and thunderstorm activity was able to slip north of the island chain to the west of the archipelago.

Whatever was left of the old front has likely become diffuse this evening. The atmospheric column will remain nearly saturated with a broad confluence zone remaining across our area. In addition, amplified upper level troughing will remain aligned through the central Gulf of America. As a result, the wetter than normal pattern will remain in and around the Keys through the overnight, and likely for a few days longer. Outside of convective influences, surface winds are expected to be light and broadly southwesterly, shifting southeast to south overnight due to the weak ridging across the area. This flow will keep surface dew points up in the mid 70s. Overnight lows will be highly dependent on convective influences, but should average out in the upper 70s to near 80.

Coastal flooding will continue at least through at least the next several days. This is due to increasing tidal amplitude and the effects of an early season King Tide. A Coastal Flood Warning remains in effect for the Upper Keys, particularly along the sounds, bay side of Key Largo. A Coastal Flood Advisory will also remain in effect for the Lower and Middle Keys.

MARINE

Issued at 925 PM EDT Mon Sep 28 2026

A much wetter than normal pattern is in place across Keys waters, lasting through the night and for at least the next several days. As result, periods of poor visibility, locally strong and gusty winds, and thunderstorms can be expected. Aside from convective influences, surface winds will be gentle out of the southwest, becoming southeast to south overnight due to the western flank of a sloppy pressure ridge remaining across our area.

AVIATION

(00Z TAFS) Issued at 925 PM EDT Mon Sep 28 2026

A wetter than normal pattern is in place across the Keys. As a result, periods of sub VFR conditions are expected at the island terminals. There is also a good chance that these periods will be accompanied by thunderstorms. Outside of convective influences, surface winds will generally be gentle out of the southwest, shifting southeast to south.

KEY WATCHES/WARNINGS/ADVISORIES

FL...Coastal Flood Warning until 5 AM EDT Tuesday for FLZ076. Coastal Flood Advisory until 5 AM EDT Tuesday for FLZ077-078.

GM...None.