textproduct: Key West

KEY MESSAGES

- High chance for showers and thunderstorms this evening as a low level trough moves into the area.

- Heat will be the primary weather concern over the next seven days. Heat indices may creep towards 110 beginning this weekend.

- A Saharan Air Layer will begin spreading across the Keys later this weekend into next week, keeping rain and thunder chances slight at best.

MARINE

Issued at 322 PM EDT Fri Jul 10 2026

Showers with embedded thunderstorms have increased in coverage across the Straits of Florida, the Southeast Gulf, and the nearshore waters surrounding the Lower Keys. An easterly undulation is in the process of entering and transiting our waters. This feature will maintain an enhanced chance for showers and thunderstorms through the evening and gradually subside after midnight. As the wave exits to the west, high pressure will slide back in from the Atlantic. This will initially maintain gentle to moderate east to southeast breezes. As the high continues to slide westward and eventually weakens, we will see breezes further slacken to light to gentle.

AVIATION

(18Z TAFS) Issued at 322 PM EDT Fri Jul 10 2026

Coverage of showers and thunderstorms will steadily increase through the remainder of the afternoon and early evening. Expecting activity to quickly diminish after midnight. Any passing shower or thunderstorm will bring a risk of MVFR to sub-IFR conditions, along with gusty erratic winds.

PREV DISCUSSION

Issued at 117 AM EDT Fri Jul 10 2026

A wetter stretch has begun to move across the Keys area this evening. This is due to an upper level low over the central Bahamas driving a couple of weak lower level troughs and associated increase in moisture and instability. The first round is working its way across the Keys tonight. A squall recently moved through the Lower Keys and further activity is congealing off the Middle and Upper Keys. Otherwise, moderate to fresh breezes are being driven by a narrow but healthy Atlantic ridge reaching westward across Central Florida and along the Gulf Coast. This is keeping temperatures slightly above normal with highs near 90, lows in the mid 80s and dew points in the mid to upper 70s.

The second trough will be carried westward ahead of the responsible upper level low through today and tonight. All guidance is pointing to at least one round of vigorous showers and thunderstorms sweeping through the forecast area from this afternoon into this evening. Hence, mid to high chance pops are being advertised. There is a good chance PoPs may be raised further in the next forecast cycle. Synoptically speaking, the ridge will remain across Central Florida, keeping east to southeasterly breezes moderate to fresh across the Key. Outside of convective influences, temperatures will continue above normal with highs with little to no day to day trend evident.

All guidance points to much drier lower level invading the area beginning saturday as a Saharan Air Layer moves in. Expect increasing low level inhibition and precipitable water falling to near 1.5 inches. As a result, rain chances will slip to slim or lower this weekend through early next week. The Atlantic ridge will weaken and become poorly defined through the first half of the week, allowing winds to trend slowly downwards. Surface temps and moisture will remain nearly unchanged through this period.

PRELIMINARY POINT TEMPS/POPS

Key West 83 93 83 92 / 40 10 10 0 Marathon 83 90 84 90 / 40 10 10 0

KEY WATCHES/WARNINGS/ADVISORIES

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