National Weather Service Marine Forecast FZUS52 KKEY

FZUS52 KKEY 182025
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
425 PM EDT Wed Mar 18 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.

Wave Detail will include details about the period and direction of origin for the highest energy waves. Long-period swells coming from a different direction than the wind would be included in the Wave Detail.

GMZ005-190830
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas 425 PM EDT Wed Mar 18 2026

SYNOPSIS
High pressure building in behind the recent frontal passage will maintain fresh to occasionally strong breezes through at least Thursday. Rain chances will remain elevated through the week with the best chances for thunder across the Straits of Florida. Breezes will slacken appreciably beginning Friday, with light to gentle breezes expected for the weekend.

The Approximate Shoreward Edge of the Gulf Stream as of March 16...

36 NM South of Dry Tortugas Light...on Loggerhead Key. 49 NM South of Cosgrove Shoal Light...off the Marquesas Keys. 31 NM South of Sand Key Light...off Key West. 16 NM South of Looe Key...off Big Pine Key. 14 NM Southeast of Sombrero Key Light...off Marathon. 7 NM Southeast of Alligator Reef Light...off Islamorada. 4 NM Southeast of Molasses Reef Light...off Key Largo. 6 NM Southeast of Carysfort Reef Light...off Ocean Reef.

Gulf Stream Information Courtesy of the National Weather Service in Key West based on products from NASA SPoRT and RTOFS.

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GMZ031-190830
Florida Bay including Barnes Sound, Blackwater Sound, and Buttonwood Sound
425 PM EDT Wed Mar 18 2026

SMALL CRAFT ADVISORY IN EFFECT

TONIGHT
North to northeast winds near 20 knots. Bay waters rough. A chance of showers.

THURSDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Bay waters rough, becoming choppy. A slight chance of showers.

THURSDAY NIGHT
North to northeast winds near 20 knots. Bay waters rough. A slight chance of showers.

FRIDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Bay waters rough, becoming choppy. A slight chance of showers.

FRIDAY NIGHT
Northeast winds 15 to 20 knots, decreasing to near 15 knots. Bay waters choppy, becoming a moderate chop.

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

SATURDAY NIGHT
Northeast to east winds near 10 knots. Bay waters a light chop.

SUNDAY
East winds 5 to 10 knots. Bay waters smooth to a light chop.

SUNDAY NIGHT
East winds near 10 knots. Bay waters a light chop.

MONDAY AND MONDAY NIGHT
Northeast to east winds 5 to 10 knots. Bay waters smooth to a light chop.

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GMZ032-035-190830
Bayside and Gulfside from Craig Key to west end of Seven Mile Bridge
Gulf of America from west end of Seven Mile Bridge to Halfmoon Shoal out to 5 Fathoms
425 PM EDT Wed Mar 18 2026

SMALL CRAFT ADVISORY IN EFFECT

TONIGHT
North to northeast winds near 20 knots. Seas 2 to 4 feet, occasionally to 5 feet, except 5 to 6 feet, occasionally to 8 feet west of the Marquesas Keys. Nearshore waters rough. A chance of showers.

THURSDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Seas 3 to 5 feet, occasionally to 6 feet, except 4 to 6 feet, occasionally to 8 feet west of the Marquesas Keys. Nearshore waters rough, becoming choppy. A slight chance of showers.

THURSDAY NIGHT
North to northeast winds near 20 knots. Seas 2 to 4 feet, occasionally to 5 feet, except 4 to 5 feet, occasionally to 6 feet west of the Marquesas Keys. Nearshore waters rough. A slight chance of showers.

FRIDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Seas 2 to 4 feet, occasionally to 5 feet, except 4 to 5 feet, occasionally to 6 feet west of the Marquesas Keys. Nearshore waters rough, becoming choppy. A slight chance of showers.

FRIDAY NIGHT
Northeast winds 15 to 20 knots, decreasing to near 15 knots. Seas 2 to 3 feet, except 3 to 4 feet west of the Marquesas Keys. Nearshore waters choppy, becoming a moderate chop.

SATURDAY
Northeast winds 10 to 15 knots. Seas 2 to 3 feet, subsiding to 1 to 2 feet. Nearshore waters a light to moderate chop.

SATURDAY NIGHT
Northeast to east winds near 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop.

SUNDAY
East winds 5 to 10 knots. Seas around 1 foot, except 1 to 2 feet west of the Marquesas Keys. Nearshore waters smooth to a light chop.

SUNDAY NIGHT
East winds near 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop.

MONDAY AND MONDAY NIGHT
NOrtheast to east winds 5 to 10 knots. Seas around 1 foot. Nearshore waters smooth to a light chop.

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GMZ042>044-190830
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
425 PM EDT Wed Mar 18 2026

SMALL CRAFT ADVISORY IN EFFECT

TONIGHT
North to northeast winds 20 to 25 knots. Seas 2 to 4 feet, occasionally to 5 feet, except 4 to 5 feet, occasionally to 6 feet west of Cosgrove Shoal Light. Nearshore waters very rough. A chance of showers.

THURSDAY
North to northeast winds 20 to 25 knots, decreasing to near 20 knots. Seas 2 to 4 feet, occasionally to 5 feet, except 4 to 5 feet, occasionally to 6 feet west of Cosgrove Shoal Light. Nearshore waters very rough, becoming rough. A slight chance of showers.

THURSDAY NIGHT
North to northeast winds near 20 knots. Seas 2 to 3 feet, except 4 to 5 feet, occasionally to 6 feet west of Cosgrove Shoal Light. Nearshore waters rough. A slight chance of showers.

FRIDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Seas 2 to 3 feet, except 4 to 5 feet, occasionally to 6 feet west of Cosgrove Shoal Light. Nearshore waters rough, becoming choppy. A slight chance of showers.

FRIDAY NIGHT
Northeast winds 15 to 20 knots. Seas 2 to 3 feet, except 3 to 4 feet, occasionally to 5 feet west of Cosgrove Shoal Light. Nearshore waters choppy.

SATURDAY
Northeast winds near 15 knots, decreasing to 10 to 15 knots. Seas 2 to 3 feet. Nearshore waters a moderate chop, becoming a light to moderate chop.

SATURDAY NIGHT
Northeast to east winds near 10 knots. Seas subsiding to 1 to 2 feet. Nearshore waters a light chop.

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

SUNDAY NIGHT
East winds near 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop.

MONDAY AND MONDAY NIGHT
Northeast to east winds 5 to 10 knots. Seas 1 to 2 feet. Nearshore waters smooth to a light chop.

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GMZ052>055-072>075-190830
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
425 PM EDT Wed Mar 18 2026

SMALL CRAFT ADVISORY IN EFFECT

TONIGHT
North to northeast winds 20 to 25 knots. Seas 6 to 9 feet, occasionally to 11 feet. Wave Detail: Northeast 8 feet at 7 seconds and west 3 feet at 8 seconds. A chance of showers with a slight chance of thunderstorms.

THURSDAY
North to northeast winds 20 to 25 knots. Seas 6 to 9 feet, occasionally to 11 feet. Wave Detail: Northeast 8 feet at 7 seconds and west 1 foot at 7 seconds. A chance of showers.

THURSDAY NIGHT
North to northeast winds near 20 knots. Seas 5 to 8 feet, occasionally to 10 feet. Wave Detail: Northeast 7 feet at 7 seconds. A slight chance of showers.

FRIDAY
North to northeast winds near 20 knots. Seas 4 to 7 feet, occasionally to 9 feet. A slight chance of showers.

FRIDAY NIGHT
Northeast winds 15 to 20 knots. Seas 4 to 6 feet, occasionally to 8 feet. A slight chance of showers.

SATURDAY
Northeast winds near 15 knots. Seas 4 to 6 feet, occasionally to 8 feet, subsiding to 3 to 5 feet, occasionally to 6 feet.

SATURDAY NIGHT
Northeast to east winds 10 to 15 knots, decreasing to near 10 knots. Seas 2 to 4 feet, occasionally to 5 feet.

SUNDAY
East winds near 10 knots. Seas subsiding to 2 to 3 feet.

SUNDAY NIGHT
East winds 10 to 15 knots. Seas 2 to 4 feet.

MONDAY AND MONDAY NIGHT
Northeast to east winds near 10 knots. Seas 2 to 3 feet.

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GMZ033-034-190830
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
425 PM EDT Wed Mar 18 2026

SMALL CRAFT ADVISORY IN EFFECT

TONIGHT
North to northeast winds near 20 knots. Seas 4 to 6 feet, occasionally to 7 feet. Wave Detail: Northwest to north 5 feet at 6 seconds. A slight chance of showers.

THURSDAY
North to northeast winds near 20 knots, decreasing to 15 to 20 knots. Seas 4 to 6 feet, occasionally to 7 feet, subsiding to 3 to 5 feet, occasionally to 6 feet. Wave Detail: North to northeast 5 feet at 5 seconds and west 1 foot at 7 seconds.

THURSDAY NIGHT
North to northeast winds near 20 knots. Seas 3 to 5 feet, occasionally to 6 feet. Wave Detail: North 4 feet at 5 seconds. A slight chance of showers.

FRIDAY
North to northeast winds near 20 knots, decreasing to near 15 knots. Seas 3 to 5 feet, occasionally to 6 feet, subsiding to 3 to 4 feet, occasionally to 5 feet.

FRIDAY NIGHT
North to northeast winds near 15 knots. Seas 2 to 4 feet, occasionally to 5 feet.

SATURDAY
Northeast winds 10 to 15 knots, decreasing to near 10 knots. Seas 2 to 3 feet, subsiding to 1 to 2 feet.

SATURDAY NIGHT through Monday
Northeast to east winds 5 to 10 knots. Seas 1 to 2 feet.

MONDAY NIGHT
North to northeast winds 5 to 10 knots. Seas around 1 foot.

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DP