textproduct: Key West

KEY MESSAGES

- Heat will be the primary weather concern over the next seven days. Heat indices may creep towards 109 during the afternoons.

- A Saharan Air Layer will linger across the Keys this week, keeping rain and thunder chances slight at best.

- As we approach closer to the new moon, tide levels will rise but should remain below Coastal Flood Statement levels at this time. Persistent puddles in the typical low spots during high tide are likely saltwater.

DISCUSSION

Issued at 1001 PM EDT Sun Jul 12 2026 Mean layer analyses from CIMSS suggest deep layer ridging across the Florida Keys. The 00Z KKEY RAOB sampled 594 DM at 500 mb (also at KXMR and KMFL), only surpassed by 595 dm at Merida, MX. Water vapor imagery highlights a one-wave pattern across the CONUS, featuring a ridge out west and a trough to the east. To the south of the ridge across Cuba, Florida and the Gulf, there are screaming upper level westerlies across the Caribbean. Down low, the SFC ridge axis stretches west across south-central Florida. Satellite derived TPW moisture products and our RAOB reveal the real story, the potent Saharan Air Layer (SAL) entrenched across the Keys. This layer is thick and extends from 550 mb to 930 mb, featuring super steep lapse rates (>9 degC/km) and dewpoint depressions of 25 degC. This is about as SALy as it gets. Central Florida is on the edge of the plume, and vigorous thunderstorms spread south into South Florida this afternoon. However, the thermodynamic environment eventually became too hostile and the storms fizzled near the Everglades. The last remnants are headed offshore near Marco Island. Given the sampled vertical profile, tonight will remain dry with overnight lows in the mid 80s. The Straits of Florida likely will experience a nocturnal surge to near 15 knots, with the remaining marine locations in the 10 to 15 knot range. The inherited forecast handles things well and no updates are planned.

MARINE

Issued at 1001 PM EDT Sun Jul 12 2026 Watches, warnings, or advisories are not expected overnight. A ridge axis will stretch west across Central and South Florida over the next week, supporting gentle to moderate east to southeast breezes. The wind speeds will tend to peak in the evening and overnight hours before decreasing slightly in the morning and afternoon hours. In addition, a large area of Saharan dust will remain in place across the area for several days and this will result in a rain-free forecast through at least the middle of next week.

AVIATION

(00Z TAFS) Issued at 1001 PM EDT Sun Jul 12 2026 VFR and gentle easterly breezes will prevail at the EYW and MTH terminals. Any sheaths of clouds noted on satellite imagery are not low clouds, but high alto based near 16 kft.

PRELIMINARY POINT TEMPS/POPS

Key West 83 92 83 92 / 0 0 0 0 Marathon 83 89 83 89 / 0 0 0 0

KEY WATCHES/WARNINGS/ADVISORIES

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