textproduct: Key West

KEY MESSAGES

- Very warm and humid conditions will continue across the Florida Keys, and will lead to a moderate to high risk for heat related illnesses well into the week. - Rain and thunder chances will peak overnight through Monday, before gradually decreasing through the middle of the week.

- A period of on and off breezy conditions will began earlier tonight, and will help to mitigate some of the discomfort from warm overnight temperatures.

DISCUSSION

Issued at 1025 PM EDT Sun May 17 2026 Deep mean layer ridging continues to define weather across the Florida Keys. A high pressure system located just north of Bermuda is supporting moderate to fresh breezes across marine observation platforms around the Florida Keys. In addition, the high is funneling moisture-laden air across South Florida. This helps explain why KBYX radar scans are detecting scattered showers across the offshore waters. GOES East Total Precipitable Water scans estimate the air mass across the Keys has a total PWAT in the 1.8 to 1.9 inch range. The 00Z evening sounding also sampled an environmental PWAT just at or above the 90th percentile for the day. That accounts for one of the three ingredients for convection, moisture. The second, instability, is ample across the Keys. The evening sounding measured CAPE values above 2500 J/kg. The fact dew points across the island chain are in the mid 70s makes sense given the instability and PWAT. The limiting ingredient across the Keys is lift. Surface winds suggest a weak ridge axis is stretching from Bermuda towards South Florida, so the chance for organized lift is minimal.

What does this mean for the overnight hours? Shower chances of 30 percent are unchanged. Breezes are on track to stay moderate to fresh through at least Tuesday, though that depends on the location and strength of the Bermuda high. Sustained breezes and gusts hint towards some relief for nighttime temperatures, considering our overnight temperatures will remain warmer than normal. Summer conditions across the Keys are coming, if not already here.

MARINE

Issued at 1025 PM EDT Sun May 17 2026 Small Craft Should Exercise Caution across all Florida Keys Coastal Waters. From synopsis, high pressure centered just north of Bermuda will continue to promote moderate to fresh east to southeast breezes through the start of the week. Breezes will remain moderate to fresh through at least Tuesday before slowly slackening. Shower chances will remain in the 20 to 30 percent range through at least mid week.

AVIATION

(00Z TAFS) Issued at 1025 PM EDT Sun May 17 2026 VFR conditions will prevail at both EYW and MTH through the TAF period. Short lived periods of MVFR CIGs cannot be ruled out while showers wax and wane near the terminals. CLoud bases are near FL025. East to southeasterly surface winds at 10 to 15 knots will be capable of occasional to frequent gusts near 20 knots. Shower coverage is expected to decrease after sunrise.

KEY WATCHES/WARNINGS/ADVISORIES

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