textproduct: Key West

KEY MESSAGES

- Measurable rain chances will remain low through the weekend, only up to 10% for each forecast period.

- Conditions will remain seasonably warm and muggy, but we may see heat index values above 105F, particularly along the Upper Keys, through Friday.

AVIATION

(18Z TAFS) Issued at 132 PM EDT Thu Jun 18 2026 VFR conditions will prevail at both EYW and MTH through the TAF period. Confidence in limited shower activity will leave mention of VCSH out of the terminals through this evening. Near surface winds will be southeasterly at 5 to 10 knots.

MARINE

Issued at 1147 AM EDT Thu Jun 18 2026 No watches, warnings, or advisories are currently in effect for the Florida Keys waters. From synopsis,a weak high pressure system in the central North Atlantic will support a brief cycle of peaks and lulls over the next day or so. Then a weak frontal boundary will approach the Florida Peninsula, acting to weaken the high, and supporting a return to light to gentle breezes. Breezes may become light and variable at times, Sunday through Monday, especially across the nearshore and offshore waters north of the island chain.

PREVIOUS DISCUSSION

Issued at 426 AM EDT Thu Jun 18 2026

Another sultry overnight for the Florida Keys as temperatures as of 4 AM remain in the mid 80s with dew points in the upper 70s. This is resulting in widespread heat index values in the mid 90s currently. Prior to midnight we tied a new warm low temperatures and we are on track to do it again. Meanwhile, KBYX radar is quiet, though we are tracking some land breeze boundaries coming off both Cuba and Andros Island that are tracking northwest towards our waters. These boundaries may be enough of a trigger for a few isolated showers or even a brief thunderstorm this morning as they pass over the Middle and Upper Keys.

Expanding our scope of vision, we have a deep layer ridge centered across the west central Atlantic that extends westward into the Gulf Basin. Round the the southwestern periphery of this ridge is a weak TUTT located over east central Cuba. There's not much of a surface reflection this hour and likely will not develop one as it is expected to weaken as it pivots towards the Florida Keys later today and into this evening.

That being said, the presence of the TUTT and the remnants of Arthur will act to weaken the western edge of the ridge and bifurcate the ridge. This will leave a smaller, secondary ridge orphaned across the Gulf Basin, which will lead to a weakening pressure field and subsequent wind pattern for the Florida Keys. In fact, we could see a brief period of light and variable winds, especially Sunday into Monday.

At the same time, we will continue to see meager moisture above the boundary layer through the next several days, resulting in PoPs of 10 percent or less. In addition, we will continue to see daytime highs near 90 degrees with overnight lows in the mid 80s and dewpoints holding in the mid to upper 70s. The combination will elevated our heat risk, especially today and Friday in the Upper Keys. Here we could see heat index values approaching 108 degrees briefly in the afternoon.

KEY WATCHES/WARNINGS/ADVISORIES

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