National Weather Service Marine Forecast FZUS52 KKEY

FZUS52 KKEY 110820
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
420 AM EDT Tue Aug 11 2026

Florida Bay, Hawk Channel and Straits of Florida from Ocean Reef to south of Dry Tortugas, and the extreme southeastern Gulf of America, including The Florida Keys National Marine Sanctuary

Seas are given as significant wave height, which is the average height of the highest 1/3 of the waves. Individual waves may be more than twice the significant wave height.

The Wave Detail section highlights the period and direction of origin for the highest-energy waves, as well as any long-period swells moving in a different direction than the wind.

GMZ005-112030
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas 420 AM EDT Tue Aug 11 2026

SYNOPSIS
Ridging across Central Florida will shift southwards into Central and South Florida and weaken over the next couple of days. Gentle to moderate breezes will trend downwards to a light breeze through this period, with some directional variability creeping in. Winds are expected to freshen late in the week as the ridge lifts back into northern Florida and a broad lower level trough moves westward across our area. Expect shower and thunderstorm chances to tick up at that time.

The Approximate Shoreward Edge of the Gulf Stream as of August 7, 2026...

25 NM South of Dry Tortugas Light...on Loggerhead Key. 15 NM South of Cosgrove Shoal Light...off the Marquesas Keys. 19 NM South of Sand Key Light...off Key West. 29 NM South of Looe Key...off Big Pine Key. 16 NM Southeast of Sombrero Key Light...off Marathon. 4 NM Southeast of Alligator Reef Light...off Islamorada. 2 NM Southeast of Molasses Reef Light...off Key Largo. 1 NM Southeast of Carysfort Reef Light...off Ocean Reef.

Gulf Stream Information Courtesy of the National Weather Service in Key West, using data from RTOFS and NASA SPoRT SST.

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GMZ031-112030
Florida Bay including Barnes Sound, Blackwater Sound, and Buttonwood Sound
420 AM EDT Tue Aug 11 2026

TODAY
East to southeast winds 10 to 15 knots, decreasing to near 10 knots. Bay waters a light to moderate chop, becoming a light chop. A slight chance of showers and thunderstorms.

TONIGHT
East winds near 10 knots, decreasing to 5 to 10 knots. Bay waters a light chop, becoming smooth to a light chop. A slight chance of showers and thunderstorms.

WEDNESDAY
East to southeast winds near 5 knots. Bay waters smooth. A slight chance of showers and thunderstorms.

WEDNESDAY NIGHT
Southeast winds near 5 knots. Bay waters smooth. A slight chance of showers and thunderstorms.

THURSDAY
Southeast winds near 5 knots. Bay waters smooth. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East to southeast winds 5 to 10 knots, increasing to near 10 knots. Bay waters smooth to a light chop, becoming a light chop. A slight chance of showers and thunderstorms.

FRIDAY
East to southeast winds near 10 knots, becoming east near 15 knots. Bay waters a light chop, becoming a moderate chop. A chance of showers and thunderstorms.

FRIDAY NIGHT
East to southeast winds near 15 knots. Bay waters a moderate chop. A chance of showers and thunderstorms.

SATURDAY
East to southeast winds 10 to 15 knots. Bay waters a light to moderate chop. A slight chance of showers and thunderstorms.

SATURDAY NIGHT
East winds 10 to 15 knots. Bay waters a light to moderate chop.

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GMZ032-035-112030
Bayside and Gulf side from Craig Key to west end of Seven Mile Bridge
Gulf of Mexico from west end of Seven Mile Bridge to Halfmoon Shoal out to 5 Fathoms
420 AM EDT Tue Aug 11 2026

TODAY
East to southeast winds 10 to 15 knots, decreasing to near 10 knots. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys, subsiding t o1 to 2 feet. Nearshore waters a light to moderate chop, becoming a light chop. A slight chance of showers and thunderstorms.

TONIGHT
East to southeast winds near 10 knots, decreasing to 5 to 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop, becoming smooth to a light chop. A slight chance of showers and thunderstorms.

WEDNESDAY
East winds 5 to 10 knots, decreasing to near 5 knots in the afternoon. Seas subsiding to 1 foot or less. Nearshore waters smooth to a light chop, becoming smooth. A slight chance of showers and thunderstorms.

WEDNESDAY NIGHT
East winds near 5 knots. Seas 1 foot or less. Nearshore waters smooth. A slight chance of showers and thunderstorms.

THURSDAY
East to southeast winds near 5 knots. Seas 1 foot or less. Nearshore waters smooth. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East winds 5 to 10 knots, increasing to near 10 knots. Seas around 1 foot. Nearshore waters smooth to a light chop, becoming a light chop. A slight chance of showers and thunderstorms.

FRIDAY
East winds near 10 knots, increasing to 10 to 15 knots. Seas 1 to 2 feet. Nearshore waters a light chop, becoming a light to moderate chop. A chance of showers and thunderstorms.

FRIDAY NIGHT
East winds near 15 knots. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys. Nearshore waters a moderate chop. A chance of showers and thunderstorms.

SATURDAY
East to southeast winds 10 to 15 knots. Seas around 1 foot. Nearshore waters a light to moderate chop. A slight chance of showers and thunderstorms.

SATURDAY NIGHT
East winds 10 to 15 knots. Seas 1 to 2 feet. Nearshore waters a light to moderate chop. A slight chance of showers and thunderstorms.

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GMZ042>044-112030
Hawk Channel from Ocean Reef to Craig Key out to the reef
Hawk Channel from Craig Key to west end of Seven Mile Bridge out to the reef
Hawk Channel from west end of Seven Mile Bridge to Halfmoon Shoal out to the reef
420 AM EDT Tue Aug 11 2026

TODAY
East winds 10 to 15 knots, decreasing to near 10 knots. Seas 2 to 3 feet, subsiding to around 2 feet. Nearshore waters a light to moderate chop, becoming a light chop. A slight chance of showers and thunderstorms.

TONIGHT
East winds near 10 knots, decreasing to 5 to 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop, becoming smooth to a light chop. A slight chance of showers and thunderstorms.

WEDNESDAY
East winds 5 to 10 knots. Seas 1 to 2 feet. Nearshore waters smooth to a light chop.

WEDNESDAY NIGHT
East to southeast winds near 5 knots. Seas around 1 foot. Nearshore waters smooth.

THURSDAY
East to southeast winds near 5 knots. Seas around 1 foot. Nearshore waters smooth. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East winds 5 to 10 knots, increasing to near 10 knots. Seas building to 1 to 2 feet. Nearshore waters smooth to a light chop, becoming a light chop. A slight chance of showers and thunderstorms.

FRIDAY
East winds near 10 knots, increasing to near 15 knots. Seas 1 to 2 feet, building to around 2 feet. Nearshore waters a light chop, becoming a moderate chop. A chance of showers and thunderstorms.

FRIDAY NIGHT
East winds near 15 knots. Seas 2 to 3 feet. Nearshore waters a moderate chop. A chance of showers and thunderstorms.

SATURDAY
East to southeast winds 10 to 15 knots. Seas 2 to 3 feet. Nearshore waters a light to moderate chop. A slight chance of showers and thunderstorms.

SATURDAY NIGHT
East winds 10 to 15 knots. Seas 2 to 3 feet. Nearshore waters a light to moderate chop. A slight chance of showers.

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GMZ052>055-072>075-112030
Straits of Florida from Ocean Reef to Craig Key out 20 NM
Straits of Florida from Craig Key to west end of Seven Mile Bridge out 20 NM
Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 NM
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry Tortugas out 20 NM
Straits of Florida from Ocean Reef to Craig Key 20 to 60 NM out
Straits of Florida from Craig Key to west end of Seven Mile Bridge 20 to 60 NM out
Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal 20 to 60 NM out
Straits of Florida from Halfmoon Shoal to 20 NM west of Dry Tortugas 20 to 60 NM out
420 AM EDT Tue Aug 11 2026

TODAY
East winds near 15 knots, decreasing to 10 to 15 knots. Seas 2 to 4 feet, occasionally to 5 feet. Wave Detail: East 4 feet at 5 seconds. A slight chance of showers and thunderstorms.

TONIGHT
East winds 10 to 15 knots. Seas 2 to 3 feet. Wave Detail: East 3 feet at 5 seconds.

WEDNESDAY
East winds 10 to 15 knots, decreasing to 5 to 10 knots. Seas 2 to 3 feet. Wave Detail: East 3 feet at 5 seconds.

WEDNESDAY NIGHT
East winds 5 to 10 knots. Seas 1 to 2 feet.

THURSDAY
East winds 5 to 10 knots. Seas 1 to 2 feet. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East winds 10 to 15 knots. Seas 2 to 3 feet. A slight chance of showers and thunderstorms.

FRIDAY
East winds near 10 knots, increasing to near 15 knots. Seas 2 to 3 feet. A chance of showers and thunderstorms.

FRIDAY NIGHT
East winds near 15 knots. Seas 2 to 4 feet, occasionally to 5 feet. A chance of showers and thunderstorms.

SATURDAY
East winds 10 to 15 knots. Seas 2 to 3 feet. A slight chance of showers and thunderstorms.

SATURDAY NIGHT
East winds 10 to 15 knots. Seas 2 to 4 feet, occasionally to 5 feet.

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GMZ033-034-112030
Gulf of America from East Cape Sable to Chokoloskee 20 to 60 NM out and beyond 5 fathoms
Gulf of America including Dry Tortugas and Rebecca Shoal Channel
420 AM EDT Tue Aug 11 2026

TODAY
East to southeast winds 10 to 15 knots, becoming east 5 to 10 knots this afternoon. Seas 2 to 3 feet, subsiding to 1 to 2 feet. Wave Detail: East to southeast 2 feet at 4 seconds. A slight chance of showers and thunderstorms.

TONIGHT
East winds 5 to 10 knots. Seas subsiding to 1 to 2 feet. Wave Detail: East 1 foot at 3 seconds. A slight chance of showers and thunderstorms.

WEDNESDAY
East winds 5 to 10 knots, becoming northeast in the afternoon. Seas 1 to 2 feet. Wave Detail: East 1 foot at 3 seconds. A slight chance of showers and thunderstorms.

WEDNESDAY NIGHT
Northeast winds near 5 knots. Seas 1 foot or less. A slight chance of showers and thunderstorms.

THURSDAY
Northeast to east winds near 5 knots. Seas 1 foot or less. A chance of showers with a slight chance of thunderstorms.

THURSDAY NIGHT
Northeast winds 5 to 10 knots, becoming east. Seas building to 1 to 2 feet. A slight chance of showers and thunderstorms.

FRIDAY
East winds 5 to 10 knots. Seas 1 to 2 feet. A chance of showers and thunderstorms.

FRIDAY NIGHT
East winds increasing to 10 to 15 knots. Seas 1 to 2 feet. A chance of showers and thunderstorms.

SATURDAY
East to southeast winds near 10 knots. Seas 1 to 2 feet. A slight chance of showers and thunderstorms.

SATURDAY NIGHT
East winds 10 to 15 knots. Seas 1 to 2 feet. A slight chance of showers and thunderstorms.