textproduct: Key West

KEY MESSAGES

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

- Rain and thunder chances will gradually return to near normal over the weekend through early next 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 1021 PM EDT Fri Aug 21 2026 Generally light southeast breezes persist across the Florida Keys. Broad high pressure in the Gulf, a weakened cold front stretched across the southeastern US, and the central Atlantic High located west of the Azores means the gradient across the Keys are maintaining the light breezes. Radar-wise, the KBYX radar detected very few meteorological objects this evening. Satellite observations from GOES East suggest the only clouds present across the Keys were decaying cirrus and the occasional cumulus. Stargazers in the Keys will appreciate the drier air, but the light winds and lack of breezes suggests that radiational cooling will be a consideration tonight for the largest islands of the Keys.

The 00Z KKEY sounding sampled an environment with weak low level steering flow, below five knots, and an amount of precipitable water below the 10th percentile for the day. In one day, the amount of moisture sampled over Key West dropped by over half an inch. Comparing the moisture in the sounding, generally southerly winds, and lingering dry air in the 850 to 500 mb layer per Advected Layer PW calculations gives an explanation as to why the skies are so clear. Tonight, expect low end rain and thunder chances, if showers are even able to form, amidst light breezes.

MARINE

Issued at 1021 PM EDT Fri Aug 21 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. This will promote generally light to gentle southeast to south breezes through Sunday, becoming variable at times during the afternoon hours. While North Atlantic ridging builds westward, southeasterly breezes will become more established for Sunday night through the middle of next week, becoming gentle and at times moderate during the overnight hours.

AVIATION

(00Z TAFS) Issued at 1021 PM EDT Fri Aug 21 2026 VFR conditions will prevail at both EYW and MTH for the upcoming forecast period. Near surface winds will be generally light southeasterlies with occasional VRBL periods. Tomorrow, the best chance for a vicinity shower would be possible island cloud line formation near EYW in the afternoon.

KEY WATCHES/WARNINGS/ADVISORIES

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