textproduct: Key West

KEY MESSAGES

- Coastal flooding will continue to gradually decrease over the weekend, but receding rates will be slow, especially in the Upper Keys.

- A wet, stormy period will continue through tomorrow. Locally heavy rainfall, especially when coincident with high tides, will exacerbate coastal flooding hazards.

- Much drier conditions are expected for Tuesday through the remainder of the work week.

DISCUSSION

Issued at 1255 PM EST Sun Nov 1 2026 The sun rose on a much more active day than expected for the Florida Keys. Widespread showers and thunderstorms were able to develop across the western half of the Florida Keys. Peak rainfall totals were observed between eastern Key West and Big Coppitt Key. Accumulation totals between 2 and 5 inches of accumulation were estimated based on MRMS and unofficial rain gauges across the Lower Keys. The atmosphere ended up being too saturated to observe hazardous wind gusts. Advected Layer PWAT satellite estimates showed deep plumes of moisture from the surface through 500 mb across the Keys. Point being, a lot of moisture existed in the environment. The atmosphere finally stabilized over the Lower Keys by noon. Showers and thunderstorms will still be able to wax and wane from the Towers to the Middle and Upper Keys, but deep convective thunderstorms are less likely this afternoon.

What was going on this morning, and why did we observe such heavy rainfall across the Lower Keys? Deep layer ridging set up over the eastern United States. The surface high associated with this ridge set up over New England. In the meantime, a shortwave trough set up over the northeastern Gulf. The trough was able to weaken the pressure gradient across southern Florida just enough to slacken the breezes across the Florida Keys. Breezes were also able to veer slightly to the southeast, and the combination of wind speed convergence and directional confluence was sufficient to sustain vigorous thunderstorms. Meanwhile, the upper altitude trough provided a source of upper altitude divergence to further fuel convection.

What happens tonight and tomorrow? The shortwave trough is stuck in a region of broad upper level ridging and will not be able to move east quickly. Upper altitude dynamics are likely to remain over the Keys through tomorrow at the latest. The problem is that the US High will move further into the Atlantic. The pressure gradient is expected to continue to weaken across the Keys, suggesting the wind speed convergence will become less focused. Breezes will be stronger on the northern end of the CWA, which suggests shower coverage will be higher closer to south Florida. More rounds of showers and thunderstorms are possible for the island chain and the nearshore waters.

Weather conditions are expected to calm down quite a bit after Monday for the Florida Keys. Eastward movement of the Atlantic High and a pronounced trough over the central United States will act to direct most of the energy from the Gulf into the eastern US. The upper level trough will linger, but without a broad source of lift, breezes are expected to slacken to light to gentle by mid-week.

Late in the week, model ensembles suggest a frontal boundary associated with the central United States trough will pass across the Florida Keys. The problem is that right now, models do not show consensus on where and when the front will move across the island chain. One group of model ensembles suggests dew points could drop into the mid 60s, while another does not lower dew points below near 70. We will keep monitoring this feature. While this forecaster would appreciate dew points lowering into the 60s, that is not a guarantee, and check back later in the week for more updates!

MARINE

Issued at 1025 AM EST Sun Nov 1 2026 Small Craft Should Exercise Caution headlines are in effect for the eastern portions of Hawk Channel and the Florida Straits. Otherwise, there are no watches, warnings, or advisories in effect for the local waters. However, an increase in shower and thunderstorms activity throughout this afternoon and tonight will result in localized hazardous marine conditions including gusty and erratic strong winds, confused seas, and occasional lightning strikes.

From synopsis: a broad area of high pressure over the eastern United States continues to sustain gentle to moderate breezes across the Florida Keys waters this weekend. Occasionally, fresh breezes are possible. Small Craft Should Exercise Caution headlines are in effect for the eastern portions of Hawk Channel and the Florida Straits. Stronger winds along the east coast will also generate an elevated northerly swell for the waters south of the Upper Keys. Shower chances will continue to remain high through Monday due to broad wind convergence across the Keys. Breezes are on track to slacken during the middle of the week as drier air moves into the Keys.

AVIATION

(18Z TAFS) Issued at 1255 PM EST Sun Nov 1 2026 Although a lull in shower and thunderstorm activity will continue through at least the early evening hours, additional development is anticipated after 06z Monday morning. Have included a window with PROB30 for TSRA at both terminals, when the most likely thunderstorm redevelopment is expected, which would be accompanied by gusty winds, MVFR ceilings, and IFR or even brief LIFR visibilities. Radar trends will be monitored, with more specific impacts to be included in possible TEMPOs and even prevailing FM groups.

CLIMATE

On this day in Keys Weather History, in 2005, 4.14" of rain fell in Key West in the early morning hours. With streets and storm drains clogged with debris only a week after Hurricane Wilma, the heavy rain caused significant flooding throughout the city. Precipitation records for Key West date back to 1871.

PRELIMINARY POINT TEMPS/POPS

Key West 75 83 76 84 / 80 60 40 30 Marathon 76 84 77 85 / 80 70 50 30

KEY WATCHES/WARNINGS/ADVISORIES

FL...Coastal Flood Advisory until 5 AM EST Monday for FLZ076>078.

GM...None.