textproduct: Key West

KEY MESSAGES

-Light to gentle breezes will prevail through tonight as high pressure continues to meander over Florida.

-Near seasonable temperatures will persist today with little to no chance of rain along with dew points in the mid to upper 60s. -The next cold front will push through the Florida Keys on Tuesday. While lacking much in the way of precipitation, it will likely deliver the coldest temperatures seen thus far.

AVIATION

(18Z TAFS) Issued at 150 PM EST Mon Dec 29 2025 VFR conditions will prevail at both EYW and MTH for the rest of today and into tonight. Northeast breezes will back to the northwest to north tonight with frequent wind gusts to 15 to 20 knots starting as early as 11z to 12z. While some showers cannot be ruled out with the approaching cold front tomorrow morning, low coverage will keep mention out of the TAFs for now.

MORNING UPDATE

Issued at 1120 AM EST Mon Dec 29 2025 An uneventful last Monday of the year is underway across the Florida Keys. KBYX radar is clear of any precipitable echoes this morning as clear skies are observed over the island chain via GOES-19 visibile imagery. A field of fair weather cumulus ripples in the Straits of Florida along a few lazy boundaries with very little movement and vertical growth. Meanwhile, broadly north light to gentle breezes persist along the Reef. Temperatures on the island chain have already warmed into the mid 70s and are on track to be above normal today with highs approaching the upper 70s. Dew points in the upper 60s to near 70 are not making it feel like dry season at the surface today, but CIMSS MIMIC PW shows only moderately dry values (less than inch) around the Keys.

Conditions are similar to yesterday in the Keys today as a surface high continues to meander over Florida. This morning's KKEY sounding looks similar to that of 24 hours ago with an inversion below 850 mb and drier air aloft suppressing convective development. Thus, another day of near nil PoPs are on tap. Tonight, the pattern starts to change as the high is pushed south by an approaching cold front. Breezes will back to the northwest to north and freshen a little this evening in preparation, but the actual edge of the approaching front is expected to arrive in the Keys sometime tomorrow morning. This will bring breezy conditions along with dime PoPs as some prefrontal convection is possible early with the extra speed convergence. Temperatures will also take a hit as highs in the lower 70s early in the day are expected to gradually decrease throughout the day. All in all, the forecast is on track with no changes required at this time.

PREVIOUS DISCUSSION

Issued at 404 AM EST Mon Dec 29 2025 A pressure ridge straddling the Florida Peninsula is resulting in light to gentle north to northeasterly breezes this morning. Lower to mid level ridging remains across our area and is helping to keep skies mostly clear with no precipitation. Temperatures are a touch above normal with dew points edging upwards into the upper 60s. Meanwhile a mid latitude trough is pushing eastward through eastern North America and an associated cold front is advancing quickly southeastward through the eastern and southeastern United States.

Mild conditions will persist today into tonight as the ridge across Florida retreats southeastward into the Keys and begins to surrender to the advancing front. Winds will remain light. While surface moisture has climbed, inhibition and dry air aloft will keep rain chances out.

The weather is expected to change noticeably when the front moves through on Tuesday. Expect northwest to north breezes to freshen considerably as a following cold high pours southward through the central and eastern United States. This will bring with it much cooler and drier air. After highs in the lower 70s early Tuesday, temperatures will slide down through the day with lows in the upper 50s by Wednesday morning. The Upper Keys will likely be several degrees cooler due to mainland influences. Dew points should fall well into the 40s. Rain chances with this front is expected to be slim at best due to diffluent flow from the surface through lower levels. The best chance will be along a rope cloud just ahead of the front.

The responsible cold high will continue to press southward into the western Gulf through mid week keeping our flow generally northerly. Winds will trend downwards through this period, but a subtler surge is likely Thursday morning due to a South Florida land breeze. Cool to cold temperatures will linger with morning lows remaining in the 50s and highs somewhere in the 60s. Thereafter the high will slowly slog its way eastward allowing for a slowly veering flow and moderating temperatures.

MARINE

Issued at 404 AM EST Mon Dec 29 2025 Winds will remain light as high pressure across Florida will shift southward across the Keys as it breaks down today into tonight. This will be followed by the passage of a fairly strong cold front, bringing with it freshening northwest to northerly breezes. Small Craft Advisories may be required as early as tonight for the deep gulf waters and early Tuesday for most remaining waters. Winds will likely be somewhat delayed over our easternmost zones as a result of a South Florida Shadow. However, they should join the SCA Tuesday night. Thereafter, high pressure centered over Texas will swing southeast then east through the Gulf, resulting in moderating and very slowly veering breezes.

CLIMATE

On this day in 1894, the high temperature in Key West was only 48F and the low temperature was 44F, both records for the date. With an average temperature of 46F, this is the coldest day ever recorded in Key West. The 48F reading is the coldest high temperature on record, and the only occasion on which the high in Key West has failed to reach 50F. Temperature records for Key West date back to 1871.

PRELIMINARY POINT TEMPS/POPS

Key West 67 73 59 69 / 10 10 0 0 Marathon 66 73 56 66 / 10 10 0 0

KEY WATCHES/WARNINGS/ADVISORIES

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