textproduct: Key West

KEY MESSAGES

- Conditions remain somewhat favorable for an island cloud line and associated waterspouts tomorrow afternoon.

- Rain and thunder chances will gradually return to near normal by the early to middle part of the week.

- Highs near 90 and dewpoints in the mid to upper 70s suggest afternoon heat indices will peak at 105 to 108 degrees.

DISCUSSION

Issued at 1016 PM EDT Sun Aug 23 2026 Weather across the Keys this afternoon proved more eventful than Saturday. A thunderstorm complex formed just north of the Lower Keys out of a couple cumulus streams late in the afternoon. The outflow boundaries created by these showers initiated another sequence of thunderstorms, one north of Marathon and the other just off Key West. The problem is that the broad col region that defined weather across the Keys for the past few days was still present. All the thunderstorm complexes this afternoon and evening were nearly stationary. This resulted in some very high MRMS estimates north of the island chain, from 1.5 to 1.8 inches in 3 hours. Accumulations of 0.5 to 0.9 were estimated over the northernmost parts of Big Pine Key, Big Torch Key, Cudjoe Key, and Upper Sugarloaf Key.

Sunset marks the downward trend in shower activity. The KKEY 00Z sounding was released shortly after showers dissipated. The balloon sampled an environment with nearly 2 inches of PWAT and quite a bit of inhibition. A similar environment can be inferred north of Marathon and the Lower Keys. Satellite observations, such as the CIMSS MIMIC TPW derivations, estimated lower PWAT values, between 1.6 and 1.8 over the Keys waters. More moisture is slowly moving into the Keys. However, moisture alone will not set off additional showers and the environment near the Keys has become somewhat stabilized. Convective models suggest the most likely time showers would form again around the Keys would be near sunrise. Considering PoPs for the rest of the night are near 10%, opting to leave the forecast alone.

TROPICS: The National Hurricane Center (NHC) continues to monitor 2 areas across the Atlantic Ocean with none of these systems currently posing a threat to the Keys. The area across the Eastern Tropical Atlantic has a low or near 0 percent chance of formation over 48 hours with a medium or 50% chance of development over the next 7 days.

MARINE

Issued at 1016 PM EDT Sun Aug 23 2026 No watches, warnings, or advisories are in effect for the Florida Keys coastal waters.

From synopsis, a split ridge pattern remains in place across the Florida Keys coastal waters. East to southeast breezes will become more established from late tonight through Thursday, becoming generally gentle, at times moderate during the overnight hours, as North Atlantic ridging builds westward. Shower chances will gradually increase to near normal values by early to mid week.

AVIATION

(00Z TAFS) Issued at 1016 PM EDT Sun Aug 23 2026 SHRA near EYW were sufficient to require VCTS for the first hour of the TAF period. However, SHRA collapsed shortly after sunset, and VFR conditions will prevail at both EYW and MTH for the rest of the TAF period. Variable winds are on track to stabilize as light east to southeasterlies before sunrise. There is a chance that SHRA may form north of the terminals before sunrise, but confidence is not high enough to include VCSH in the TAFs.

PRELIMINARY POINT TEMPS/POPS

Key West 84 91 84 91 / 10 10 10 30 Marathon 83 91 82 91 / 10 10 20 30

KEY WATCHES/WARNINGS/ADVISORIES

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