textproduct: Key West

KEY MESSAGES

- A Saharan Air Layer is moving across the Florida Keys. The SAL is on track to lift out of the Keys by the weekend.

- Heat will be the primary weather concern this week. Heat indices may creep towards 110 before the weekend.

- Shower coverage is expected to increase at the end of the week while a low in the upper atmosphere tracks westward across the Keys.

DISCUSSION

Issued at 1010 AM EDT Wed Jul 8 2026 A drier pattern is setting up across the Florida Keys this morning. A glance at the sky indicates a washed out, or milky, color amidst a general lack of cloud cover. The morning 12Z KKEY sounding offered an explanation, the Saharan Air Layer moved over the Florida Keys before sunrise. The sounding sampled a pronounced inversion just above 4000 feet and a dry adiabatic lapse rate to 700 mb. Satellite observations from CIMSS also show a distinct layer of drier air over the Florida Keys. While the SAL will define part of the weather this afternoon, that is not the only weather feature of note. Breezes across the reef freshened to gentle to moderate before sunrise. Last night's slight northward movement of the Atlantic ridge could let moderate to fresh breezes develop across the southern waters of the Florida Keys. In sum, relatively expect minimal shower coverage, sustained southeasterly breezes, and reduced visibility from the Saharan air. No changes are necessary for the forecast.

MARINE

Issued at 1228 AM EDT Wed Jul 8 2026

A surface Atlantic ridge stretching westward across the Florida Peninsula has now lifted northward into Central Florida. This with the ridge strengthening slightly will help to freshen breezes across Keys waters over the next few days. Breezes will tend to peak in the evening hours and lull during the day. At least cautions will be required periodically for portions of Keys waters through this stretch. Winds will trend downwards this weekend as the ridge weakens.

From synopsis, winds will trend upwards over the next couple of days as the Atlantic ridge across Central Florida strengthens. Light to gentle breezes will become moderate to fresh by tonight. Winds will tend to peak in the evenings and lull slightly during the day. At least marine cautions will be required to most Keys waters over the next few days. Breezes are expected to ease back gradually through the weekend. Shower and thunder chances will be slight or less over the next few days, but trend sharply upwards late in the week as a weak low level trough pushes westward across our area.

AVIATION

(12Z TAFS) Issued at 1010 AM EDT Wed Jul 8 2026 VFR conditions will prevail at EYW and MTH for the upcoming period. Winds are expected to freshen in the late afternoon and overnight. VIS will be slightly reduced by the presence of the Saharan Air Layer over the Florida Keys, but not to the point of MVFR VIS.

PREV DISCUSSION

Issued at 1228 AM EDT Wed Jul 8 2026 The Atlantic ridge will remain across Central Florida and help drive moderate east to southeasterly breezes across the Keys. A few hours of breezy conditions will be likely in the very late afternoon and evening hours and tend to lull during the day. Forecast soundings indicate a healthy dose of lower level inhibition and drying based just above 900 mb. This should help to keep rain and thunder chances slight to nil over the next couple of days. Expect highs to remain near 90 and lows in the lower to mid 80s. Rather humid conditions will persist due to dew points remaining in the mid to upper 70s.

Through the latter portion of the week and into the weekend, a cut off upper low will wobble its way westward across the Central Bahamas and into Cuba. An associated lower level trough is still expected to work its way across our general area late in the work week and the start of the weekend. While guidance has been trending weaker with the inverted trough, they still depict subtle and messy lower level troughing and associated swathes of increasing moisture. Expect rain and thunder chances to pick up Thursday night and lingering into the weekend. Winds should trend downwards slightly through this period as the surface ridge lifts further northward and weakens slightly.

The lower levels are expected to dry out considerably beginning in the second half of the weekend, allowing rain and thunder chances to come down. Weakening ridging will try to hold on across the Florida Peninsula and keep breezes generally gentle to moderate east to southeasterly.

PRELIMINARY POINT TEMPS/POPS

Key West 91 84 91 83 / 20 10 0 20 Marathon 90 84 90 83 / 20 0 0 30

KEY WATCHES/WARNINGS/ADVISORIES

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