textproduct: Key West

KEY MESSAGES

- Near to slightly-above normal rain chances in the short term is expected to give way to considerably higher rain chances later in the work week.

- Winds are expected to trend upwards over the next several days, likely peaking in the moderate to fresh range around mid week.

- 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 400 AM EDT Tue Sep 15 2026

A weak split surface ridge lingers across Florida this morning. As a result, surface winds are light out of the east to southeast. Last evenings sounding indicated deep layered moisture remains quite high with 2.19 inches of precipitable water. This was slightly above the 90th percentile for the date. While there was ample CAPE, weak inhibition and weak forcing has kept activity isolated across the area through much of the night. More recently, scattered showers have begun percolating across our zones. On the larger scale, a strong mid and upper level ridge is currently building across the eastern United States while sharp troughing is digging southward off the Atlantic Coast.

Over the next couple of days, a robust continental high will spread south and southwestward through the southeastern United States and gradually bolster the local pressure gradient. Expect light east to southeasterly breezes to freshen modestly later this afternoon and evening out of the northeast to east. Deep layered moisture is expected to slip slightly through the day with weak lower level inhibition holding on. As a result, expect near normal shower and thunder chances today. Island cloud lines will once again be possible. Temperatures will remain trend less with highs near 90 and lows in the lower 80s. Dew points will hold in the mid 70s.

The tail end of the sharp trough digging off the Atlantic coast is expected to pinch off and interact and absorb a TUTT cell moving in across Hispaniola and the Central Bahamas through the middle portion of the week. As a result, deep layered moisture is expected to increase across and east of our area as broad lower level troughing takes shape. The mid and upper level low and lower level trough is expected to sweep westward into our area through the back half of the week. In addition, the mid and upper low complex will result in falling heights aloft. Expect shower and thunder chances to trend sharply upwards through the middle of the week, likely peaking in the Thursday time frame. Breezes will gradually relax and veer east to southeast as the trough pushes through.

It may take some time for the copious atmospheric moisture to clear out of our area. The trough/low complex should slowly lumber westward into the Gulf while broad ridging sets up off the Atlantic Coast. This will keep a broad moist confluent zone across our area for quite some time. Consequently, a prolonged period of above normal rain chances are possible through late week and weekend. With all that said, the evolution of these features are highly uncertain as is often the case with complex upper level interactions. that said, uncertainty is high and model to model and run to run disagreement is high.

MARINE

Issued at 400 AM EDT Tue Sep 15 2026

Weak and splintered high across Florida will be steadily reinforced and ultimately absorbed by a strong continental high spreading southward through the eastern United States. Light to gentle easterly breezes will begin freshening later this afternoon and evening out of the northeast to east, becoming a moderate breeze. Winds are likely to peak this evening and tomorrow evening. Broad troughing set to take shape over the Central Bahamas over the next several days will then migrate westward across the Keys region through the back half of the week. Breezes will slacken and steadily veer east to southeast. Along with this trough, expect increasing moisture and shower and thunder chances to increase sharply after mid week and fall back towards normal heading into the weekend.

AVIATION

(00Z TAFS) Issued at 400 AM EDT Tue Sep 15 2026

VFR conditions will prevail at the island terminals today. Shower and thunder chances will be near normal. Surface winds will be light to gentle out of the east. Winds are expected to begin strengthening modestly out of the northeast to east this afternoon and evening.

KEY WATCHES/WARNINGS/ADVISORIES

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