textproduct: Key West

KEY MESSAGES

- Rain chances will only reach 10% over the next several days.

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

DISCUSSION

Issued at 357 AM EDT Wed Jun 17 2026

Another mundane overnight for the Florida Keys. A broad ridge centered southeast of Bermuda extends well to the west across the entire Gulf Basin. This has kept the Keys under generally southeast to south flow at the surface. Despite a somewhat moist southerly flow, we main locked under large scale subsidence. This in turn is inhibiting most of our shower potential. This southerly flow is also responsible for our muggy overnight with temperatures holding in the mid 80s and dew points in the upper 70s. The combination of which is making for heat index values in the lower to mid 90s!

Meanwhile Potential Tropical Cyclone (PTC) 1 has moved out in the extreme western Gulf Basin off the coast near Corpus Christi and continues to slowly move northeast this morning towards southeast TX and southwest LA.

The aforementioned ridge will continue to dominate our sensible weather through much of the next 7 days. PTC 1 will ride along the edge of said ridge and move inland across LA and MS over the coming days. Meanwhile, surface flow will continue from the south keeping the boundary layer moist. However, despite the moisture in the lowest levels, we will have to contend with pockets of drier air just above the boundary layer. This combined with the deep layer subsidence, will make it highly unlikely for showers or an isolated thunderstorm to get going. The impacts instead will be the increasing heat risk. Heat index values for Tuesday reached and exceed 100 degrees and is expected to reach higher values today through Friday, especially across the Upper Keys.

A quasi-stationary frontal boundary that lies along and north of the North Gulf Coast will meander southward towards the end of the week and into the weekend. This will act to weaken the ridge and lead to slackening winds over the weekend. Winds could briefly go light and variable Saturday into Sunday before the ridge gradually re-builds and winds return solidly from the east and southeast. Meanwhile, moisture will continue to be limited along with large scale subsidence holding in place. This will keep rain chances at 10 percent at best through the foreseeable future.

MARINE

Issued at 357 AM EDT Wed Jun 17 2026

Gentle to occasional moderate southeast to south breezes this morning will gradually and briefly slacken to light to gentle by the late afternoon and early evening. Breezes will then freshen slightly and return to gentle to moderate overnight. Thereafter, breezes will tend to peak during the late evening and then lull in the afternoons through Friday afternoon. A weak frontal boundary will approach the Florida Peninsula towards the end of the week, the high will once again weaken, supporting a return to light to gentle breezes and potentially light and variable briefly, for the weekend.

AVIATION

(06Z TAFS) Issued at 357 AM EDT Wed Jun 17 2026

VFR conditions expected with light to gentle southeast to south winds. An isolated shower or thunderstorm may develop near or the east of the MTH terminal, but confidence is too low to mention in the current TAF cycle.

PRELIMINARY POINT TEMPS/POPS

Key West 91 82 91 82 / 0 20 10 0 Marathon 88 82 89 83 / 10 10 10 0

KEY WATCHES/WARNINGS/ADVISORIES

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