textproduct: Key West

KEY MESSAGES

- Peak rain and thunder chances are expected today with decreasing rain chances expected for tonight, though still above normal as the active pattern continues.

- Light to gentle west to northwest breezes expected this morning becoming mainly westerly this afternoon and tonight.

- Heat indices may approach 105 to 110 degrees each afternoon for some Florida Keys island communities, especially in the Upper Keys.

DISCUSSION

Issued at 1200 PM EDT Mon Jul 27 2026 It has been a busy morning across the Florida Keys as weather remains unsettled! Deep troughing has provided upper level support for showers and thunderstorms this morning, with many waking up just before sunrise thanks to the rolling thunder. CIMSS Mean Layer analysis shows the trough axis just barely to our east, so we are still in the thick of it with respect to the vertical profile providing support. Our 12Z KKEY sounding from this morning comes with the caveat that it likely intercepted an outflow boundary near the surface, so some of the values calculated may not necessarily be representative of the area. With that being said, an exceptionally wet profile was sampled with a PWAT value of 2.31", which is three hundredths greater than the daily maximum value of 2.28". MRMS 3-hour radar derived rainfall accumulations highlight the Middle Keys where a slow-moving line of thunderstorms this afternoon may have produced up to an inch of rainfall. THe most efficient showers stayed offshore where our local marine life may have enjoyed up to 2 to 3 inches of rainfall.

With the environment still primed for more activity, and while the trough axis slowly crawls eastward, things should keep up for the next few hours before gradually waning. No changes are needed to the inherited forecast.

DISCUSSION

Issued at 445 AM EDT Mon Jul 27 2026 Surface troughing will remain across the Eastern Seaboard and the western North Atlantic today and tonight, and will keep moisture locked in across the area. Slightly drier air will move in late tonight, resulting in rain chances dropping to slightly above normal (40%). Another trough is expected to swing down from Canada sliding across the Great Lakes, Northeast, and Mid- Atlantic. This will reinforce the current troughing already in place. At the surface, a frontal boundary will remain draped across North Florida and Georgia for the next several days. This is quite unusual for this time of the year. Due to this, it will keep a fairly unsettled pattern across north to central Florida as the moisture focuses across this area. Drier air is expected to move into the Keys due to the ridge across the Atlantic leading to decreasing rain chances. The heat will become the main story again especially from mid week onward. Daytime highs will be in the lower 90s and overnight lows in the lower 80s with some mid 80s from mid to late week. Dew points in the mid to upper 70s will lead to heat index values of 105 to 110 degrees.

Breezes will freshen to gentle to moderate as the high across the Atlantic and the front across Florida act in tandem with one another leading to an increased pressure gradient, especially for mid week. After mid week, the gradient relaxes some and breezes relax back to light to gentle.

MARINE

Issued at 1200 PM EDT Mon Jul 27 2026 Widely spread showers with embedded thunderstorms will lead to locally stronger winds and higher seas/rougher waters at times across virtually all of our marine zones today. The strongest activity will be capable of producing gusty and erratic winds of 25 to 30 knots, blinding downpours, and frequent lightning strikes. Otherwise, activity should very gradually diminish as the environment becomes worked over. Outside of this activity, generally light to moderate west to northwest breezes will back to the southwest to west tonight with a 40 percent chance of showers and thunderstorms.

AVIATION

(15Z TAFS) Issued at 1200 PM EDT Mon Jul 27 2026 Unsettled weather will lead to period of MVFR CIGs throughout the TAF period, but background VFR conditions should prevail. Isolated pockets of stronger showers and thunderstorms will continue to move through the area, and could bring very infrequent and short lived IFR to LIFR conditions. Due to the low confidence regarding when, and if, these categorical changes will occur, opting to keep the prevailing TAFs VFR with VCSH, and will adjust for significant impacts if needed.

PRELIMINARY POINT TEMPS/POPS

Key West 89 82 90 82 / 60 30 40 20 Marathon 89 81 91 82 / 70 50 50 20

KEY WATCHES/WARNINGS/ADVISORIES

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