textproduct: Key West

KEY MESSAGES

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

- A dry air mass will linger over the Florida Keys during the rest of the holiday weekend. Shower coverage tonight is on track to decrease until Monday night.

- A weak frontal passage is expected across the Keys sometime Monday night/Tuesday. This will lead to slightly cooler temperatures, a drop in dew points, and increased shower chances.

DISCUSSION

Issued at 320 PM EDT Sun Oct 11 2026 The flow field across the Florida Keys finally began to change this morning. GOES East water vapor satellite observations indicate there is a pronounced moisture gradient currently over the Florida Keys. Dry air associated with a rebuilding subtropical ridge slowly moved over the nearshore and offshore waters this morning, as evidenced by estimates of environmental PWAT from GOES-East. There is a gradient of approximately 1.5 inches to around 2.2 inches from the Upper Keys to the Lower Keys. The problem was that mixture between heavily saturated and drier air across the Keys was enhancing instability over the Outer Gulf waters. The extensive amount of moisture observed by this morning's 12Z KKEY sounding, nearly 2.5 inches of precipitable water, existed in an atmosphere with little to no inhibition. The source of lift provided by weakly confluent flow in the lower levels allowed thunderstorms to develop just northwest of Key West. However, as the drier air stabilizes over the Florida Keys, one can expect shower coverage to decrease. The other issue for showers this afternoon and tonight is that this dry layer is stuck above the surface layer. Even though skies are on track to clear, dew points are forecast to remain in the upper 70s to near 80 across the island chain. Tonight is setting up to be another muggy, humid night for the Keys.

There are a couple of points of uncertainty this week. First, a frontal boundary extending from a large mid-latitude cyclone, the remains of Major Hurricane Isaias, is primed to stall near the Florida Keys during the early part of the week. Statistical guidance suggests the front will be able to move south of the island chain, but exactly how much temperatures and dew points will drop remains uncertain. While a few days ago, statistical models suggested dew points could decrease to the upper 60s, the near 70 to the lower 70s appears more likely for the island chain. Breezes are expected to freshen to gentle to moderate after frontal passage. Shower coverage is expected to pick back up sometime midweek.

The most notable feature for the forecast is what models are resolving over the weekend. Deterministic models suggest a potent front could move across the Keys on Saturday to Sunday. However, the seven day forecast is a bit far out. Expect this forecast to change quite a bit as we get closer to the weekend.

MARINE

Issued at 320 PM EDT Sun Oct 11 2026 There are no watches, warnings, or advisories currently in effect for the nearshore or offshore waters of the Florida Keys. Boaters should be aware of less clearance under fixed bridges around times of high tide as a Coastal Flood Statement is in effect for the Florida Keys. Breezes slackened to gentle to moderate southeasterlies across the reef as a drier air mass moved over the eastern waters.

From synopsis: A couple of nearby features will define the weather across the Florida Keys for the first half of the week. The Atlantic Ridge is gradually weakening and moving east towards the central Atlantic. Another weak high pressure system is located over the Gulf. Between the two pressure systems a a weak frontal boundary that is set up across central Florida. The front is primed to pass across the Keys waters sometime early in the week, and promote gentle to moderate northeast to east breezes. Shower chances are forecast to be slight before mid-week before the previously mentioned front stalls near the Keys waters. Late in the week, there is a chance a strong cold front could develop and move towards the Florida Keys. Frontal passage with this cold front could occur over next weekend, and we will continue monitoring this system.

AVIATION

(18Z TAFS) Issued at 320 PM EDT Sun Oct 11 2026 Some isolated, but very light, showers will remain near EYW near 18Z, but these will diminish quickly. Impacts onsite are not expected. VFR conditions will prevail at both island terminals through the TAF period with only FEW skies near FL020. Surface winds out of the southeast near 10 knots will gradually back to the east tonight, becoming northeasterly near the end of the 18Z TAF period.

CLIMATE

On this day in 1909, the daily record rainfall of 8.94" was recorded in Key West as a Category 3 Hurricane moved rapidly northeast from the western tip of Cuba along and just south of the entire length of the Keys. It caused nearly a million dollars in damage in Key West, drowned 12 railroad workers, and destroyed about 400 buildings. Sand Key recorded a minimum pressure of 28.37" with winds estimated at 100 mph before being swept out to sea. Rainfall records for Key West date back to 1871.

PRELIMINARY POINT TEMPS/POPS

Key West 81 90 78 87 / 10 20 40 20 Marathon 82 90 79 88 / 20 20 40 20

KEY WATCHES/WARNINGS/ADVISORIES

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