textproduct: Key West

KEY MESSAGES

- A Coastal Flood Statement is in effect, and particularly low lying areas will see some saltwater ponding around the times of high tide.

- Major Hurricane Isaias in the Gulf does not pose a direct threat to the Florida Keys, but it will bring increasing westerly swell into the region for the first half of the weekend.

- Winds will be elevated over the waters surrounding the Lower Keys early this evening.

- Increasing moisture across the Keys tonight through Saturday night will lead to higher rain chances. The peak in activity is expected tonight.

DISCUSSION

Issued at 315 PM EDT Fri Oct 9 2026 Major Hurricane Isaias, now a Category 3 hurricane, is forecast to make landfall along the Florida Panhandle tonight. While direct impacts to the Florida Keys are not expected, the tropical cyclone is modifying the environment around the Keys. Breezes along the reef were able to build to fresh southeasterlies because Major Hurricane Isaias intensified and moved further east than previously forecast. Wave heights in the Outer Gulf waters and the western Florida Straits are higher than normal due to the hurricane. Significant wave heights west of the Dry Tortugas may become as high as 7 feet this afternoon. Even when the hurricane moves inland, waves within the Gulf will continue to be amplified through the first half of the weekend.

While the hurricane is the most prominent weather feature nearby, it is not the only pattern of interest for the Florida Keys. A tropical upper tropospheric trough (TUTT) is spinning south of central Cuba. Over the past few days, the TUTT has slowly made its way west across the Caribbean. During the middle of the week, it came into phase with a weak wave in the lower atmosphere located over Hispaniola and eastern Cuba. CIMSS satellite derived vorticity was able to track this impulse to just south of the Bahamas.

This afternoon, showers were relatively sparse across the Florida Keys. Major Hurricane Isaias generated a region of sinking air around it, which kept shower activity low over South Florida. Cloud cover is gradually starting to increase across the Keys waters, however, as the previously mentioned wave moves towards South Florida. GOES East satellite observations show building cumulus coverage over the Straits of Florida. Tonight, there are a couple of changes to expect. Hurricane Isaias will move further from the Florida Keys, which will allow breezes to slacken across the western waters. The region of sinking air generated by the hurricane will also follow the storm. Shower coverage is expected to increase when the drier air aloft shifts away. The first half of the upcoming weekend looks rainy, so brace for showers and thunderstorms.

There are a couple of features to monitor for next week. First, high pressure is expected to build over the southeastern US after Major Hurricane Isaias moves north and transitions into a mid latitude system. A front extending from the former hurricane is expected to move south and stall near the Florida Keys early next week. While a temperature change is less likely, dew points may be able to decrease towards the lower to mid 70s by mid week. Mean layer winds will not remain northeasterly, and by next Friday we may be back in a moist pattern across the Keys. Check back again over the weekend, because any forecast in the wake of a major hurricane will be prone to more uncertainty than usual. For now, take precautions where necessary!

MARINE

Issued at 315 PM EDT Fri Oct 9 2026 Small Craft Should Exercise Caution until winds decrease for the Outer Gulf waters and the western Straits of Florida due to elevated winds and swell generated by Major Hurricane Isaias. A Small Craft Advisory was required for the westernmost waters this morning, but winds have slackened as the hurricane moved further north. Breezes across the reef have stabilized as gentle to moderate southeasterlies with periods of moderate to fresh gusts.

From Synopsis: Major Hurricane Isaias is forecast to make landfall in northern Florida tonight. Elevated swells generated by the hurricane will persist through the Florida Straits and the outer Gulf waters through the first half of the weekend. Breezes are on track to slacken while Hurricane Isaias moves north. Meanwhile, a plume of moisture will move north from eastern Cuba tonight and increase shower and thunderstorm chances. Breezes will be able to slacken during the first half of the weekend. Next week, expect breezes to wax and wane as high pressure develops over the southeastern United States.

AVIATION

(18Z TAFS) Issued at 315 PM EDT Fri Oct 9 2026 VFR conditions will prevail at EYW and MTH for the upcoming TAF period. SHRA near the terminals will become more likely tonight as Major Hurricane Isaias moves further north. Near surface winds will slacken tonight, but gusts and elevated crosswinds will be a concern until tomorrow morning. Cloud coverage will increase during the evening, but MVFR to IFR conditions are not expected outside of nearby SHRA.

CLIMATE

On this day in 2009, the daily record warm low temperature of 84F was recorded in Key West. Temperature records for Key West date back to 1872. On this day in 2009, the daily record warm low temperature of 83F was recorded in Marathon. Temperature records for Marathon date back to 1951.

OF NOTE At Pennekamp State Park: In 2011, a rainfall of 11.02" was recorded.

PRELIMINARY POINT TEMPS/POPS

Key West 80 89 80 89 / 50 40 60 30 Marathon 81 88 82 88 / 60 30 40 20

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...Small Craft Advisory until 4 PM EDT this afternoon for GMZ033-034- 055-075.