textproduct: Key West

KEY MESSAGES

- Moisture will linger across the region through the end of the week, supporting rain and thunderstorm chances.

- 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 index values will range from 100-108 degrees daily with little relief from the muggy conditions overnight. Know the signs of heat stress, take frequent breaks, and stay hydrated.

DISCUSSION

Issued at 103 AM EDT Thu Sep 10 2026

Elongated surface through mid level ridging is aligned over the southeastern United States. At the surface, this has allowed for mostly gentle easterly breezes to build in across the Keys. Deep layered moisture remains quite high with last evenings sounding indicated the precipitable water was around the 75th percentile at 2 inches with seasonable instability. The environment has been supportive of scattered showers with embedded thunderstorms. The latest round of activity is in the process of visiting much of the Florida Keys. Temperatures are near normal with dew points muggy in the upper 70s.

Rain chances are set to remain above normal in the near term. A swath of enhanced moisture is expected to push through the Keys, and guidance hints at some cyclonic curvature through the lower levels. the HRRR is fairly enthusiastic about shower and thunderstorm coverage today and appears to be at least partially driven by quite a bit of convergence near the Central Bahamas. As a result, have nudged PoPs up to likely for today. The ridge will remain the dominant synoptic player and surface winds will remain mostly gentle east to southeasterly through much of the day, but is expected to strengthen modestly this evening. Expect near to slightly above normal temperatures with dew points remaining sticky in the upper 70s.

Rain chances should fall considerably to slight or low chance tonight as a band of drier air with weak 850 mb inhibition is expected to push through the area. This lull in coverage is expected to be fairly short lived as lower level moisture quickly climbs again early Friday, along with continued weak cyclonic curvature tucked in under the ridge. As a result, expect a return to slightly above normal rain chances. Breezes will gradually shift southeasterly and slacken slightly as the surface ridge is expected to retreat further into the Atlantic while the axis shifts down across the Peninsula.

Through early next week, the lower level ridge will be reinforced by a continental high marching eastward behind a mid latitude trough. The ridge is expected to setup quite a bit further north across the southern states. Should this occur, the ridge's tradewind belt will lift into our area and easterly breezes should freshen modestly. Unidirectional easterly flow along the southern Periphery of the deep layered anticyclone will hopefully allow rain chances to slip closer to normal.

MARINE

Issued at 103 AM EDT Thu Sep 10 2026

Atlantic ridging stretching westward through the Southeast and Florida will maintain gentle to moderate mostly easterly breezes on Keys waters through the next couple of days. Breezes are expected to tip subtly further southeasterly and weaken heading into this weekend as the body of the ridge retreats into the Atlantic. Shower and thunderstorm chances will be elevated in the short term. Through the early portion of next week the ridge will be reinforced by a new high cell following a mid latitude trough eastward across the eastern United States. This will mainly help to keep breezes gentle to moderate out of the east.

AVIATION

(06Z TAFS) Issued at 103 AM EDT Thu Sep 10 2026

VFR conditions will prevail at the island terminals today. With that said, a wetter than normal period is expected today and there is a better than even chance for bouts of showers and potential thunderstorms at the terminals. Surface winds will be light to gentle out of the east to southeast.

PRELIMINARY POINT TEMPS/POPS

Key West 92 82 92 82 / 70 30 50 30 Marathon 90 84 90 83 / 60 30 40 50

KEY WATCHES/WARNINGS/ADVISORIES

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