textproduct: Key West

KEY MESSAGES

- Drier air associated with a weak early season cold front will arrive early tomorrow, resulting in below normal rain chances with dew points falling towards 70.

- Light northerly breezes will freshen late tonight, becoming gentle to moderate for a few hours in the morning.

- Increasing northeasterly swell in the wake of the cold front will allow seas to build to 4 to 5 feet by the end of the week, especially in the easternmost Straits of Florida.

DISCUSSION

Issued at 623 PM EDT Thu Sep 24 2026

The shift towards drier weather that began over the past couple of days will continue overnight. Sharp deep layered ridging remains broadly aligned over the northwestern Gulf and adjacent States as a deepening mid latitude trough lifts slowly slowly northward off the Mid-Atlantic coast. This arrangement has placed broad lower level diffluence across our area and considerable drying has taken place through the mid and upper levels. This evenings sounding indicated precipitable water has fallen significantly over the past 24 hours to around 1.8 inches, slightly below the daily mean. These changes were reflected in the considerably weaker and diminished coverage of this afternoon and evenings convective activity. Only a few showers have dotted the area through the evening. Winds are light and northwesterly as the tail end of an old surface trough is steadily dragged further northeastward out of the Keys region.

Through the overnight, robust high pressure blanketing the eastern United States will spread southward while the mid latitude trough continues to lift further northward along the Atlantic Coast. The building high is expected to push a weak early season cold front southward through the Keys late tonight. Guidance is hinting at winds freshening slightly late in the night, briefly becoming gentle to moderate north to northeasterlies towards sun- up. Expect slight rain chances due to falling moisture and anticyclonic flow finally gaining dominance across our area. It is still very early in the season and no significant trend in temperatures are expected. Overnight lows should settle in the upper 70s to near 80 with dew points holding in the mid 70s. It is worth mentioning that dew points are on track to slip towards 70 by early this weekend.

MARINE

Issued at 623 PM EDT Thu Sep 24 2026

Lingering surface troughing will finally be pulled northeastward out of our area as high pressure builds southward across Florida and the Gulf. This will keep winds light out of the northwest to north for much of the night. Expect breezes to freshen modestly late in the night and early tomorrow as a very early season weak cold front pushes into our waters. There is a chance cautions may be briefly required for our deep gulf zones. Otherwise, no cautions or advisories are expected.

AVIATION

(18Z TAFS) Issued at 623 PM EDT Thu Sep 24 2026

VFR conditions will prevail at the island terminals overnight. Surface winds will be light out of the northwest to north, strengthening slightly out of the north late.

KEY WATCHES/WARNINGS/ADVISORIES

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