textproduct: Key West

KEY MESSAGES

- Rain chances will be near zero for the island chain through most of, if not the rest of, the week.

- Light and variable winds will eventually assume a northwest to northerly direction by this evening, and will gradually veer to the east to southeast by Wednesday morning.

- Dew points may increase to the mid 70s by the end of the week, and this will bring about some heat risk concerns as these will be the first prevailing higher dew points of the season.

DISCUSSION

Issued at 1037 AM EDT Tue May 5 2026 A weak, lingering boundary is still somewhere across the very distant Florida Straits as noted by a broken line of clouds and isolated pockets of showers. The parent troughing has taken its time to nudge eastward away from us, but CIMSS Mean Layer Wind analysis confirms the trough is slowly crawling away. Shower activity has gradually tapered off over the past few hours, and the 12Z KKEY sounding suggests we may be in the clear with respect to anymore rainfall. Even though there is some low level moisture present, there are so many weak inversions through the profile, that the temperature line looks like a Christmas tree. The wind profile through the shallow moisture is backing from north to west, and the environment is generally unfavorable for any notable, longstanding shower activity. Temperatures along our island communities are in the mid 80s with dew points in the lower to mid 70s. This gives us noontime heat index values near 90F, so it looks like our first real taste of summertime is on our doorstep.

The only change made to this afternoon update is to remove the slight chance, 10%, of showers for the Keys. No other changes are proposed at this time.

MARINE

Issued at 1037 AM EDT Tue May 5 2026 There are no watches, warnings, or advisories in effect for the Florida Keys local waters. Light and variable winds will continue through the afternoon, eventually becoming generally northwest to north. An occasional light shower may pop up across the distant Florida Straits due to a residual boundary, otherwise chances for showers and thunderstorms remain near zero.

AVIATION

(15Z TAFS) Issued at 1037 AM EDT Tue May 5 2026 VFR conditions will prevail at both island terminals, but occasional unrepresentative observations of MVFR CIGs are possible due to cloud formation directly over either airport. Light and variable surface winds will eventually assume a northwest to northerly direction, but crosswind concerns are low due to the low magnitude of these winds. Dry weather will continue through the TAF period.

PREV DISCUSSION

Issued at 400 AM EDT Tue May 5 2026 Robust mid to upper level ridging will amplify over the next couple of days as it drives eastward through the Gulf. This will result in rising mid level heights and considerable drying through the column. As a result, a few showers this morning should give way to rain free weather by tonight. Winds will remain light and often variable today into tonight as the weak trough slowly dissipates and ridging begins building southwestward across Florida. With nothing to kick out the in-situ airmass, expect temperatures to largely remain slightly above normal with highs in the upper 80s and lows in the upper 70s.

The mid to upper level ridge will continue to push eastward and be aligned across Cuba on Thursday and flatten as it transitions into the Atlantic. Precipitable water will fall to slightly below normal with a nose of low level inhibition strengthening. As a result, rain chances will remain out of the forecast through the remainder of the work week. At the same time, Atlantic surface ridging will broaden as it becomes better established across South Florida. In response, winds will become light to gentle southeasterlies. This flow will bring in warmer and more humid air. Expect highs in the upper 80s, overnight lows struggling to fall below 80, and dew points climbing into the muggy mid 70s range.

Uncertainty is fairly high heading into the weekend. A new shortwave trough will begin swinging eastward through eastern United States, flattening the upper level ridge. The lower level ridge will be pinched southeastward across Cuba and the Bahamas and setup a moistening and increasingly confluent flow. Meanwhile the surface ridge will expand northward and help to bring in freshening southeasterlies. Altogether, this will open the door to isolated to possibly scattered showers. Day time highs may slip a degree or two while overnight lows will be near or slightly above 80.

PRELIMINARY POINT TEMPS/POPS

Key West 86 77 87 79 / 10 0 0 0 Marathon 85 77 86 79 / 10 0 0 0

KEY WATCHES/WARNINGS/ADVISORIES

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