textproduct: Key West

KEY MESSAGES

- King Tides are expected to result in minor saltwater flooding of low elevation streets and lots. Don't drive through flood roadways!

- Moderate to occasionally fresh northerly breezes may occur in the southeastern Gulf waters over the next several hours this morning. Small craft should exercise caution in the Gulf until winds decrease.

- Increasing northeasterly swell in the wake of a cold front will allow seas to build to 4 to 5 feet today through the weekend, especially in the easternmost Straits of Florida.

DISCUSSION

Issued at 455 AM EDT Fri Sep 25 2026

Mid to upper-level water vapor imagery reveals a deepening trough axis situated off the Mid-Atlantic coast while a sharp moisture gradient, extending southwest from the western Atlantic across Andros Island and through the Straits of Florida, helps to roughly delineate where the frontal boundary is currently located. Meanwhile, broad ridging to our west continues to slowly sink southward along the Texas coast. The 00Z KKEY RAOB sampled the early proliferation of dry air, especially above 500mb, but some drying is noted below 500mb as well. Currently, there are scattered showers and a thunderstorm or two being initiated by a wind surge and weak surface convergence along the front in the waters west and south of the Lower to Middle Keys. This activity is struggling to grow vertically due to the dry air aloft, and only a handful of lightning strikes have occurred. Deep west to northwesterly flow will continue to advect dry air further south towards Cuba throughout the day with the front expected to settle across the Straits. Expect freshening breezes to gentle to moderate today in the wake of the front. Hi-res guidance suggests moderate to fresh breezes may occur in the southeastern Gulf for a short period this morning, but winds are expected to slacken throughout the day. Small craft should exercise caution in the Gulf until winds decrease. Additionally, northerly swell will result in building seas of 4 to 5 feet today into the weekend in the easternmost Straits of Florida off the Upper Keys. To round things off, as we approach a peak in the astronomical tides, minor saltwater flooding is expected to occur during high tide along the Keys. This may be compounded by a backup of the Gulf stream due to the strengthening system parked off the East Coast. A Coastal Flood Statement remains in effect through this afternoon for the Florida Keys, and extensions into the coming days may be necessary.

As we head into the weekend, the early season nor'easter will continue to strengthen and loiter along the New England coast. Embedded shortwaves rotating south through the mean troughing will provide reinforcing surges of dry air into Florida and across the Keys on Saturday. This will also help to provide at least some measure of mid to upper level cyclonic flow across the area, but showers/storms will be limited in coverage and vertical growth by the preceding dry airmass in place. As such, the forecast generally calls for below-normal rain chances for the next few days. Slight chances will be focused in the Straits of Florida near the stalled front, or in the Florida Bay and Upper Keys associated with any southward moving activity from the Florida mainland. Guidance continues to trend towards lower dewpoints in the upper 60s to lower 70s Saturday afternoon into Sunday along the Island Chain with temperatures running perhaps a couple of degrees lower than usual. Not a wild temperature swing, but certainly noticeable from a lower humidity perspective.

By early next week we will begin to gradually transition back into more of a wet pattern as low-level Atlantic ridging begins to expand across the area, allowing low-level winds to swing back to south- southwesterly. This will help to force tropical moisture northward across the Keys as the remnant front completely washes out. However, in the mid to upper-levels troughing associated with the East Coast low will begin to once again amplify across the Southeast and into the Gulf, placing the Florida Keys and surrounding waters back into a favored zone for lift. This is likely to become maximized by the middle of next week in which above-normal PoPs are expected to develop.

MARINE

Issued at 455 AM EDT Fri Sep 25 2026 From synopsis, scattered showers and perhaps a thunderstorm will track towards the south over the Florida Keys waters this morning before diminishing throughout the day as a drier air mass pushes into the region behind a frontal boundary. Freshening northerly breezes are expected today, becoming gentle to moderate in the wake of the front. However, moderate to occasionally fresh breezes will be possible in the southeastern Gulf this morning before decreasing by midday, and small craft should exercise caution in the Gulf waters until winds decrease. In addition, seas across the easternmost Florida Straits will build today and into the weekend due to an incoming 4 to 5 feet northerly swell following the frontal passage. Northerly winds will gradually slacken over the weekend, especially during the daytime hours.

AVIATION

(06Z TAFS) Issued at 128 AM EDT Fri Sep 25 2026

A cold front is in the process of advancing south through the Keys with dry air also expanding across the area. An associated wind surge and weak surface convergence along the front is helping to trigger isolated SHRA near the terminals at this hour. For now, added VCSH at both sites through 12Z. Although there's a non-zero chance of a brief shower at a terminal over the next few hours, coverage and intensity will be limited by the dry air aloft. Sfc winds will prevail from the north around 5 to 10 knots with VFR expected to continue for much if not all of this TAF cycle.

KEY WATCHES/WARNINGS/ADVISORIES

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