textproduct: Key West

KEY MESSAGES

- A strong pressure gradient associated with a cold front will support a prolonged period of breezy to windy conditions across the Florida Keys.

- A Small Craft Advisory is in effect for all coastal waters for hazardous winds and seas. These conditions will last through the next several periods.

- Shower and thunder chances will decrease during the early part of the week as a dry air mass moves over the Florida Keys.

DISCUSSION

Issued at 410 AM EDT Mon Oct 19 2026 A stalled frontal system over the southern Florida Straits was able to define weather across the Keys early this morning. Shower coverage was focused over the Straits, and individual showers were able to generate individual gusts over 30 knots. Prevailing fresh to strong breezes have been measured along the reef. Water vapor satellite imagery identified a deep layer of dry air moving towards the Florida Keys. GOES-19 Total Precipitable Water returns estimated a difference of about three quarters of an inch of PWAT between the Lower Keys and Naples. CIMSS MIMIC Layer PWAT measured a similar difference. However, dew points have lingered in the lower 70s across the island chain. The dry air has not yet mixed down to the surface. However, CIMSS satellite derived winds indicate the mean layer winds this morning were northerly. Dry conditions are imminent. Until then, shallow showers will be able to wax and wane over the Florida Straits. Winds at the surface will remain elevated with breezy to windy conditions expected through tonight.

The primary question through mid-week is how long winds will remain elevated. While the northerly mid to upper level flow will keep pushing drier air south, it will take at least 36 to 48 hours for the front to dissipate. That will not bring an end to the elevated winds, however, because a strong nor'easter is developing off the outer banks at the same time a high pressure system is building over the eastern United States. While breezy to windy conditions are not anticipated to last through the entire week, light to gentle breezes are unlikely. For those on the islands, there is higher confidence that dew points will be able to drop to near 70F with occasional periods of time in the upper 60s.

MARINE

Issued at 410 AM EDT Mon Oct 19 2026 A Small craft Advisory is in effect for all the Florida Keys waters. Shallow showers will continue to be focused over the Straits of Florida through this afternoon.

From synopsis: a cold front that has stalled over the southern waters of the Florida Straits will continue to support fresh to strong breezes. Hazardous winds and seas will continue through tonight, thus a Small Craft Advisory is in effect for all the Florida Keys waters. Fresh to strong northeasterly breezes will prevail through the first half of the week. Breezes will be able to gradually slacken to moderate to fresh during the middle of the week as the front moves over Cuba. Shower chances will decrease through tonight as a drier air mass moves over the Florida Keys.

AVIATION

(06Z TAFS) Issued at 410 AM EDT Mon Oct 19 2026 VFR conditions will prevail at both EYW and MTH. Short lived periods of MVFR CIGs will wax and wane while light SHRA develop near the terminals. Timing for showers is not at high enough confidence to include TEMPOs at this time. Occasional CIGs above FL030 are possible during the day. Breezy SE winds will persist through the forecast period. Expect shifts between fresh to strong breezes with occasional gusts of 25 to 30 knots.

PRELIMINARY POINT TEMPS/POPS

Key West 86 75 86 75 / 40 20 10 10 Marathon 85 76 85 75 / 40 10 10 10

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...Small Craft Advisory until 5 AM EDT early this morning for GMZ031>035-042>044-052>055-072>075.