textproduct: Key West

KEY MESSAGES

-A chance of rain still exists today as activity over the local waters may get close to the island chain.

-Small Craft Advisories are now in effect as a cold front draped over South Florida is freshening our breezes.

-As high pressure builds in over the second half of the week, mild, mostly dry conditions will be expected with gentle to moderate breezes.

DISCUSSION

Issued at 504 AM EST Mon Dec 15 2025 Weather conditions have been mostly quiet during this overnight shift, but our KBYX radar has been detecting pockets of showers to the east and southeast of the Upper Keys. The showers closest to the Keys have been filtering in from the area just offshore of Miami, but the newest development over the Florida Straits seems to be forming along some kind of boundary. Temperatures are in the lower 70s, but frequent wind gusts near 20 mph have made it feel a little chillier than the past couple of nights. GOES-19 IR imagery shows patchy low level clouds over some of our marine zones, but the island chain is still experiencing clear skies. This is good news for our warm weather lovers, because the morning sunshine may take some of the edge off of the chill. However, cloud cover may fill in as showers increase, so expect on and off sunshine throughout today.

The most notable impact from this cold front on our sensible weather will be in our surface winds. Both NAEFS and ECMWF percentiles suggest that low level winds across our forecast area today will be close to a climatological maximum. This is a signal that simply tells us the winds in the current forecast are much higher than what an "average" forecast would hold for this time of year. While this doesn't offer an insight to just how high these winds will be, it does provide confident that we are looking at breezy to windy conditions today.

As the parent trough pivots and lifts over the coming days, breezes will start to slacken over the course of the second half of the week. Mean layer ridging will encourage a new push of moisture, but guidance is struggling to determine just how substantial this moisture will be. GFS and ECMWF ensemble members point to some chances for rainfall, but the NBM has single digit PoPs. We likely won't see this wide range of solutions come to an agreement until we clear this cold front, so we'll have to monitor how guidance trends over the next few days.

MARINE

Issued at 504 AM EST Mon Dec 15 2025 A Small Craft Advisory is in effect for all Florida Keys local waters. From synopsis, a tightening pressure gradient due to a cold frontal passage will lead to an extended period of fresh to strong breezes. Higher pressure building in during the middle of the week will cause breezes to slacken for the second half of the week, and light to gentle breezes will be in place by the weekend.

AVIATION

(06Z TAFS) Issued at 504 AM EST Mon Dec 15 2025 VFR conditions will prevail at both EYW and MTH today. While a chance of rain is in the forecast, uncertainty in exact location and timing will keep mention out of the TAFs for now. Near surface winds will be out of the north to northeast at near 10 knots with gusts to near 20 early, becoming northeast and increasing to 10 to 15 knots with gusts to 20 to 25 knots later today.

PRELIMINARY POINT TEMPS/POPS

Key West 77 68 77 70 / 30 20 10 10 Marathon 76 68 76 70 / 30 20 10 10

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...Small Craft Advisory until 5 AM EST Tuesday for GMZ031>035- 042>044-052>055-072>075.