textproduct: Key West

KEY MESSAGES

- Very warm and humid conditions over the next few days will lead to a moderate risk of heat illness with periods of major risk conditions possible. - Quick moving showers and storms may bring bursts of heavy rainfall, reduced visibility, and gusty winds.

- Gentle to moderate easterly breezes will continue for the next several days peaking in the evenings and overnight and decreasing in intensity during the afternoon hours.

DISCUSSION

Issued at 1005 AM EDT Wed May 20 2026

The latest 12z KEY upper air sounding depicts ample saturation throughout much of the low level boundary layer overlain with stout northwesterly cyclonic flow as the region remains on the far western periphery of an upper level low in the vicinity of the northwestern Bahamas this morning. Precipitable water values currently in the 1.6 to 1.8 inch range across the region are close to the 75th percentile for the date as a plume of higher atmospheric moisture content gradually slides westward via easterly surface flow. This has supported the continued development of vertically capped shower activity across the island chain this morning, briskly moving along in 10-15 knots of near surface, 850mb flow. Mesoscale models (HRRR, RRFS, etc) depict a maxima in convection across the region for the remainder of this morning before propagating outflow boundaries from existing convection and slightly drier air advecting into the region may bring a lull in activity during the afternoon hours. With the easterly flow overnight and warm sea surface temperatures, shower activity may once again pick up in coverage across the island chain and waters overnight into Thursday morning. High temperatures this afternoon will reside in the mid to upper 80s (with peak heat indices in the low to mid 90s) across the majority of the region with overnight lows tonight forecast to drop into the lower 80s.

MARINE

Issued at 1005 AM EDT Wed May 20 2026

Expansive surface high pressure across the region will result in a continuation of much of the same over the local waters, as gentle to moderate easterly wind flow continues. Wind speeds will continue to gradually decline throughout the rest of the week, however daily fluctuations (higher wind speeds in the evenings and overnight, lower wind speeds during the day) will continue. Ample moisture will support the continuation of elevated rain chances for the remainder of the week.

AVIATION

(18Z TAFS) Issued at 106 PM EDT Wed May 20 2026

Shower activity is forecast to gradually wane in coverage over the next several hours as activity shifts to the north of the region. Winds will remain out of a breezy easterly/southeasterly direction with shower activity forecast to once again increase overnight into Thursday morning. Gusty winds and reduced cigs are possible at terminals in and around shower activity.

CLIMATE

On this day in 1932, the daily record rainfall of 3.83 inches was recorded in Key West. Rainfall records for Key West date back to 1871.

On this day in 2024, the daily record rainfall of 7.08" was recorded in Marathon. This also ranks as the wettest day ever recorded in May. Rainfall records for Marathon date back to June 1950.

PRELIMINARY POINT TEMPS/POPS

Key West 90 81 91 81 / 30 20 20 20 Marathon 86 80 87 80 / 30 20 20 20

KEY WATCHES/WARNINGS/ADVISORIES

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