textproduct: Key West

KEY MESSAGES

-Light to gentle northeast to east breezes and fair weather will prevail across the Florida Keys today.

-Breezes will begin to increase tonight across the Florida Keys likely resulting in Small Craft Advisories tonight or Monday.

-Breezes should relax some mid week, though breezy conditions are expected to continue through at least Christmas Day.

DISCUSSION

Issued at 1040 AM EST Sun Dec 21 2025 Water vapor imagery highlights a slightly more amplified upper level pattern across the CONUS compared to 24-hours ago. Flanking the mean layer ridge over the Western Caribbean is a building long wave ridge over the western US. A clipper system continues to race to the northeast towards Nova Scotia, while a trailing cold front reaches into the southeastern US. The unified surface analysis places a squashed high between the Atlantic Bight and Bermuda, and a stonger 1030+ mb high spilling into the Ohio River Valley. This second high will be the next weather maker for the Florida Keys over the next several days. Freshening northeasterly breezes will overtake the Keys tonight as the southern flank of this high spreads down the Florida Peninsula. Small Craft Advisories may be required as early as tonight for the Straits of Florida, and likely will be required Monday for the remaining coastal waters of the Florida Keys.

For this afternoon, highs will climb to near 80 with gentle to moderate northeast breezes. Rain chances are near nil.

FORECAST

The main story for the majority of Christmas week will be the breezy to windy conditions that are anticipated. A series of high pressure systems will move across the eastern United States. The first of these has moved off the East Coast and is currently moving farther out into the North Atlantic. The second and strongest in the series of highs is currently moving southeastward across Minnesota, Iowa, and Wisconsin early this morning. Northeast to east breezes will begin to freshen today as the second high builds in and slides across the eastern United States. This will lead to a prolonged period of breezy to windy conditions for the Island Chain and surrounding waters beginning late tonight, peaking Monday night through Tuesday night. Breezy conditions are expected to still persist after mid week, including Christmas Eve and Christmas Day as the third high replaces the second one earlier in the week. Towards the end of the week, a developing low pressure system across the Great Lakes will lead to a flattening of the high pressure system resulting in further slackening breezes. In addition to the northeast to easterly flow, these highs will also act to steer in a modified continental air mass from the northeast. This will result in slowly lowering humidity throughout the week along with a slight dip in temperatures.

Moisture will remain rather meager for the next few periods. As breezes peak Monday night and Tuesday, it will be met with a moisture surge across the Keys. Slight chances of rain (10%) have been reintroduced into the forecast as a result. Also with the increased northeast to east flow, there is the likelihood for mainly speed convergence showers but also the possibility of confluent flow. Moisture will be quite shallow with much of it capped around 850 mb. The atmosphere quickly dries out as you increase height to around 700 mb meaning any showers that try to grow vertically will quickly entrain the dry air, choking them off. At best, these showers are expected to mostly be quick moving trace to perhaps a hundredth of an inch type activity. Drier air moves in Tuesday night onward through Christmas Day leading to nil rain chances. Slight moisture increase again late week brings slight chances back into the forecast before drying out again over the weekend.

MARINE

Issued at 1040 AM EST Sun Dec 21 2025 Small Craft Advisories may be required as early as tonight for the Straits of Florida, and likely will be required Monday for the remaining coastal waters of the Florida Keys. From synopsis, a continental high pressure cell will advance eastward from the Eastern Seaboard to the western North Atlantic today. Cold continental air will reinforce this high today and tonight, and fresh to strong northeast to east breezes will develop across all Florida Keys coastal waters by tonight continuing through Tuesday night. Mainly fresh northeast to east breezes will peak and lull Christmas Eve and Christmas Day.

AVIATION

(15Z TAFS) Issued at 1040 AM EST Sun Dec 21 2025 VFR and gentle northeast breezes will prevail at the EYW and MTH terminals through the afternoon. Northeast wind gusts near 20 knots (10-15 knot crosswind) will begin at both terminals before 12Z Monday morning.

KEY WATCHES/WARNINGS/ADVISORIES

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