textproduct: Key West

KEY MESSAGES

-Southeast to south breezes will veer towards the south and southwest overnight and slacken. Light and variable winds are possible for the island chain and nearshore waters north of the island chain.

-Light winds and a moist air mass could promote patchy fog for the island chain but more likely across the nearshore waters north of the island chain.

-Rain chances increase this evening, with thunder also possible tonight ahead of a weak frontal passage.

-Outside of modestly freshened breezes, minimal changes to the seasonably warm conditions are expected in the wake of the front.

MARINE

Issued at 114 PM EST Thu Dec 18 2025

Breezes along and south of the reef have slackened this afternoon as expected. Seeing more widespread southeast to south gentle to moderate breezes across the area this hour. Breezes will continue to slacken while veering towards the southwest overnight. Winds could go light and variable across the nearshore Gulf and Bayside waters. This would potential allow for patchy fog to develop, especially if precipitation occurs overnight. The window for fog would be small (late tonight into Friday morning), as breezes will clock around from the northwest and freshen in the wake of the next frontal passage. This front is expected to be weak and breezes will likely top out at moderate this go-around. By early next week, a strong high will shift into the eastern U.S. and will promote a stronger freshening of breezes. Mariners are encouraged to stay tune for future updates.

AVIATION

(18Z TAFS) Issued at 114 PM EST Thu Dec 18 2025

VFR conditions continue this afternoon and will prevail through the evening. Watching for showers and possibly thunderstorms to develop along and ahead of an approaching frontal boundary. Confidence remains low at this time as much of the activity may slide to the west of the terminals. However, winds will go light and variable overnight and this could allow for some patchy fog or stratus to develop. For now have introduced a SCT010-015 for both terminals, with MTH having a slightly higher chance.

PREV DISCUSSION

Issued at 448 AM EST Thu Dec 18 2025

Another quiet morning is underway across the Florida Keys. KBYX radar is once again free of precipitable echoes in our area. GOES-19 Nighttime Microphysics imagery shows a mix between patches of westerly moving fair weather cumulus in the eastern Straits and high cirrus streaking northeast across the Gulf. Moderate easterly breezes persist along the Reef having changed very little over the last few hours. Temperatures along the island chain are a couple degrees warmer than yesterday around this time and range in the lower to mid 70s with dewpoints near 70.

Some change in pattern is forecast in the short term. An elongated surface high stretching from the southeast US into the western North Atlantic will lift northeast and start losing its grip on our sensible weather today. As a result, easterly breezes will gradually slacken and veer to the southeast throughout the day. While breezes will be turning to more moist surface wind, a large pocket of dry air still exits in the lower to mid level just above the inversion observed in our 00z KKEY balloon sounding last night. Thus have opted to keep slight chance PoPs today.

Tonight could get a little more interesting as the lower to mid level profile moistens up. Forecast soundings indicate decent (for this time of year) low level shear and modestly uncapped instability. That being said, forcing will be somewhat nebulous as winds are expected to be on a downward trend with no apparent sources of synoptic lift. CAMs do suggest some isolated convection may form despite these limiting factors, so have opted to go with chance PoPs and a slight chance of thunderstorms just in case.

Our sensible weather pattern will continue to change this weekend as a cold front approaches late Friday. Breezes will clock all the way back around to the north, but due to the weak nature of the front temperatures will only see a few degrees of difference from previous days. By the start of next week, high pressure will build back along the east coast of CONUS with breezy conditions developing Monday and possibly becoming windy into Tuesday. While this solution has been relatively stable, there is still plenty of time for some changes to the forecast so stay tuned.

PRELIMINARY POINT TEMPS/POPS

Key West 73 80 69 78 / 30 20 0 10 Marathon 73 81 69 79 / 20 10 0 10

KEY WATCHES/WARNINGS/ADVISORIES

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