textproduct: Key West

KEY MESSAGES

- Better moisture is moving back in this afternoon and will continue through the evening and overnight with rain chances around 30 percent.

- 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. This will be followed by a stronger Saharan Air Layer for the weekend.

MARINE

Issued at 319 PM EDT Thu Jul 9 2026

Gentle to moderate east to southeast breezes will freshen during the late afternoon and early evening, starting in the Straits of Florida first. Small Craft Exercise Caution headlines are in effect for all of the coastal waters surrounding the Florida Keys. In addition, moisture is gradually increasing with shower coverage building across mainly the Straits of Florida. As additional moisture pools in across the region, expect coverage to increase and overspread across the remaining waters overnight through Friday. Breezes are expected to ease back gradually through the weekend. The next Saharan Air Layer pushes in over the weekend with much drier air air lingering into next week.

AVIATION

(18Z TAFS) Issued at 319 PM EDT Thu Jul 9 2026

East to southeast winds will be gradually increasing during the late afternoon and early evening. In addition, shower coverage will be gradually increasing after midnight and have inserted a line for VCSH for both terminals. MVFR or brief IFR conditions will be possible within passing showers.

PREV DISCUSSION

Issued at 1215 AM EDT Thu Jul 9 2026

Quiet weather continues across the Keys this morning. A narrow but healthy surface through lower level Atlantic ridge stretches westward across Central Florida and is driving breezy east to southeasterly flow across the Keys. This flow is holding up temperatures and current readings are in the mid to upper 80s with dew points in the mid to upper 70s. While this evenings sounding indicated a precipitable water not to far from normal at 1.67 inches, there was a robust subsidence inversion based just above 900 mb with a good slug of dry air. This has kept shower activity down to essentially non existent across our forecast area.

A cut off upper low is currently creeping its way westward through the central Bahamas and has produced a weak lower level reflection that is beginning to move across Cuba. While today will remain dry, the weak trough will push through our area beginning tonight. This will wipe out the stable and dry layer holding showers at bay. Expect a slight to low chance for showers and thunderstorms beginning tonight. East to southeasterly breezes will remain moderate to fresh, peaking in the evening and early night hours and lulling slightly during the day. This will continue to drive slightly above normal temperatures with highs near 90, lows in the mid 80s, and dew points holding in the mid to upper 70s.

The previously mentioned upper low will contribute to yet another lower level trough heading into the weekend. This will keep at least a low chance for showers and thunderstorms. Thereafter, much drier and more stable lower levels is expected to sweep in. As a result, rain chances will be slight or less from later in the weekend and well into next week.

PRELIMINARY POINT TEMPS/POPS

Key West 83 92 83 93 / 30 50 40 10 Marathon 83 90 83 90 / 30 50 40 10

KEY WATCHES/WARNINGS/ADVISORIES

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