textproduct: Key West

KEY MESSAGES

- Moisture will linger across the region through the start of the weekend, supporting slightly above normal rain and thunderstorm chances.

- The primary threat for any stronger thunderstorms will be lightning strikes. When thunder roars, go indoors. If on a boat, stay low, or go below.

- Heat index values will range from 100-108 degrees daily with little relief from the muggy conditions overnight. Know the signs of heat stress, take frequent breaks, and stay hydrated.

DISCUSSION

Issued at 400 AM EDT Fri Sep 11 2026

Surface through mid level Atlantic ridging stretches westward across Florida. The surface ridge is supporting gentle to moderate east to southeasterly breezes along the island chain this morning. Last evenings sounding indicated precipitable water above the 90th percentile at 2.33 inches. This has been the case recently due to a stubborn swath of elevated lower level moisture pervading the area. The lower levels were very moist, with minimal inhibition and ample CAPE. After clusters of shower and thunderstorms through the day and evening, activity has since all but dissipated. Some short lived low level drying and stabilizing was expected for this time period and may have contributed to the unusual lack of convection in recent hours.

Through the weekend and into next week the surface through mid level ridge will remain in control of our area. Surface winds will remain east southeasterly with moderate peaks overnight and light lulls during the day. The previously mentioned short lived drying and stabilizing is expected to be just that. Lower level moisture will recover today into tonight as another swath of elevated lower level moisture sweeps westward into our area. This will help to keep shower and thunder chances slightly above normal through the weekend. Expect near to slightly above normal conditions with highs near 90 and lows in the lower to mid 80s. Things will remain sticky with dew points in the upper 70s.

Through the first half of the week, deep layered ridging will amplify over the southeast and eastern United States while a sharp trough digs off the Atlantic Coast. At the surface the ridge will be reinforced by a robust ridge coming off the Atlantic coast and may pull freshening breezes northeast to easterly. While this may eventually lead to dew points dipping into the mid 70s, continued moisture rich lower levels, along with an accelerating confluent flow may result in a period or two of elevated rain chances. This would be around Tuesday. There is a lot of moving parts here and uncertainty is high.

MARINE

Issued at 400 AM EDT Fri Sep 11 2026

An Atlantic ridge will remain across the Florida Peninsula through the weekend and into next week. This will maintain east to southeasterly breezes. Expect the usual moderate evening and night peaks and light to gentle lulls during the day. Lower level moisture will stubbornly remain elevated through the weekend, keeping shower and thunder chances slightly higher than normal.

AVIATION

(00Z TAFS) Issued at 400 AM EDT Fri Sep 11 2026

VFR conditions will prevail at the island terminals today. There will be a chance for showers and thunderstorms in the vicinity. Surface winds will be light to gentle out of the east to southeast.

PRELIMINARY POINT TEMPS/POPS

Key West 92 82 92 81 / 50 30 60 40 Marathon 90 83 90 83 / 40 50 50 60

KEY WATCHES/WARNINGS/ADVISORIES

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