Marine Weather and Tide Forecast for Duck Key, FL

DISCUSSION
Issued at 1035 AM EDT Thu Oct 8 2026 Hurricane Isaias intensified into a Category 1 storm early this morning, making it the first hurricane of the 2026 Atlantic season. No threats are anticipated for the Florida Keys. Instead, we are seeing weather conditions associated with being on the eastern side of a tropical cyclone, but far enough away to not observe hazardous winds or rainfall. GOES-East satellite observations over the Florida Keys show nearly cloud free skies across the waters. KBYX radar returns highlight few, if any, meteorological echoes. Gentle to moderate southerly breezes were observed along the reef. Aloft, the 12Z KKEY sounding sampled a healthy amount of moisture over the Keys. The measured PWAT was well above the 90th percentile value for the day, yet the skies remain clear. Two features are likely the cause of our drier weather. The first is actually Hurricane Isaias. Hurricanes are massive heat engines, and the convection within the cyclone causes air to spread away from the system. That warm, drier air then subsides away from the hurricane. In this case, air is sinking over the Keys. The second feature would be the Cuban landmass.
Southerly winds near 10 knots favor a pattern referred to as a "Cuban Shadow." Mountains force air to rise, thunderstorms form, and a drier region sets up downstream of the mountains.

Overall, the current pattern suggests this afternoon will be uneventful. PoPs are likely to drop out of the forecast. Winds may decrease during the afternoon, but otherwise expect few changes.
Enjoy the dry conditions while they last, because we may get a pulse of showers this weekend.

MARINE
Issued at 1035 AM EDT Thu Oct 8 2026 A Coastal Flood Statement is in effect for the Florida Keys.
Boaters should be aware of less clearance under fixed bridging around times of high tide. No additional watches or warnings are in effect for the Florida Keys coastal waters.

From synopsis: Hurricane Isaias, currently over the southwestern Gulf waters, is expected to move towards the North Gulf Coast over the next few days, strengthening as it does so. A cold front remains draped across north-central Florida which will slowly press southward infringing on the surface ridge to its south. In doing so, these systems will act in tandem to create a tightening pressure gradient across the Keys, resulting in freshening mainly southeast breezes as we head into the weekend. In addition, moisture will also be on the rise leading to higher rain and thunder chances. Any showers and storms will be capable of causing hazardous marine conditions through the weekend.

AVIATION
(12Z TAFS)
Issued at 1035 AM EDT Thu Oct 8 2026 VFR conditions will prevail at EYW and MTH for the upcoming TAF period. Near surface winds will be predominantly southerly with some variation from southwest to southeast. Showers, if present, will be short lived and thus not included in the TAFs.

CLIMATE
On this day in 2020, the daily record warm low temperature of 83F was recorded in Key West. Temperature records for Key West date back to 1872. On this day in 2012, the daily record warm low temperature of 82F was recorded in Marathon. Temperature records for Marathon date back to 1950.

PRELIMINARY POINT TEMPS/POPS
Key West 88 82 88 82 / 30 20 30 70 Marathon 88 82 88 82 / 20 20 40 70

KEY WATCHES/WARNINGS/ADVISORIES
FL...None.
GM...None.