National Weather Service Marine Forecast FZUS52 KKEY

FZUS52 KKEY 211429
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
1029 AM EDT Tue Jul 21 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.

GMZ005-220230
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas 1029 AM EDT Tue Jul 21 2026

SYNOPSIS
As of 5 AM EDT, Tropical Storm Bertha was centered over the northeastern Gulf waters. Bertha is expected to continue moving slowly to the northwest or west-northwest today, followed by a turn to the west by the middle part of the week. On the forecast track, TS Bertha will move near or along the northern Gulf coast during the next several days. Closer to home, an Atlantic ridge of high pressure will extend to the Florida Peninsula for the next several days. Moderate breezes will slacken to mainly gentle this afternoon. Thereafter, breezes will continue to peak overnight and lull during the day through Friday.

The Approximate Shoreward Edge of the Gulf Stream as of July 17, 2026...

49 NM South of Dry Tortugas Light...on Loggerhead Key. 51 NM South of Cosgrove Shoal Light...off the Marquesas Keys. 38 NM South of Sand Key Light...off Key West. 22 NM South of Looe Key...off Big Pine Key. 13 NM South of Sombrero Key Light...off Marathon. 6 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.

---

GMZ031-220230
Florida Bay including Barnes Sound, Blackwater Sound, and Buttonwood Sound
1029 AM EDT Tue Jul 21 2026

THIS AFTERNOON
Southeast winds near 10 knots. Bay waters a light chop.

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

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

WEDNESDAY NIGHT
East winds near 10 knots, increasing to 10 to 15 knots. Bay waters a light chop, becoming a light to moderate chop. A slight chance of showers and thunderstorms.

THURSDAY
East winds near 10 knots. Bay waters a light chop. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East winds 10 to 15 knots. Bay waters a light to moderate chop. A chance of showers and thunderstorms.

FRIDAY
East to southeast winds 5 to 10 knots. Bay waters smooth to a light chop. A chance of showers and thunderstorms.

FRIDAY NIGHT
East to southeast winds 5 to 10 knots. Bay waters smooth to a light chop. A slight chance of showers.

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

SATURDAY NIGHT
Southeast to south winds near 5 knots. Bay waters smooth.

---

GMZ032-035-220230
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
1029 AM EDT Tue Jul 21 2026

THIS AFTERNOON
Southeast to south winds near 15 knots, becoming southeast and decreasing to near 10 knots. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys. Nearshore waters a moderate chop, becoming a light chop.

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

WEDNESDAY
Southeast winds near 15 knots, becoming east to southeast and decreasing to near 10 knots in the afternoon. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys. Nearshore waters a moderate chop, becoming a light chop. A slight chance of showers and thunderstorms.

WEDNESDAY NIGHT
East winds 10 to 15 knots. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys. Nearshore waters a light to moderate chop. A slight chance of showers and thunderstorms.

THURSDAY
East winds near 10 knots. Seas 1 to 2 feet. Nearshore waters a light chop. A slight chance of showers and thunderstorms.

THURSDAY NIGHT
East winds 10 to 15 knots. Seas 1 to 2 feet, except 2 to 3 feet west of the Marquesas Keys. Nearshore waters a light to moderate chop. A chance of showers and thunderstorms.

FRIDAY
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 chance of showers and thunderstorms.

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

SATURDAY
Southeast to south winds near 5 knots. Seas 1 foot or less. Nearshore waters smooth.

SATURDAY NIGHT
Southeast winds near 5 knots. Seas 1 foot or less. Nearshore waters smooth.

---

GMZ042>044-220230
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
1029 AM EDT Tue Jul 21 2026

THIS AFTERNOON
Southeast to south winds near 15 knots, becoming southeast and decreasing to near 10 knots. Seas 2 to 3 feet. Nearshore waters a moderate chop, becoming a light chop.

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

WEDNESDAY
Southeast winds near 15 knots, becoming east to southeast and decreasing to near 10 knots. Seas 2 to 3 feet. Nearshore waters a moderate chop, becoming a light chop. A slight chance of showers and thunderstorms.

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

THURSDAY
East winds near 10 knots. Seas 2 to 3 feet. Nearshore waters a light chop. A slight chance of showers and thunderstorms.

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

FRIDAY
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 chance of showers and thunderstorms.

FRIDAY NIGHT
East to southeast winds 5 to 10 knots. Seas around 1 foot. Nearshore waters smooth to a light chop. A slight chance of showers.

SATURDAY
Southeast to south winds near 5 knots. Seas around 1 foot. Nearshore waters smooth.

SATURDAY NIGHT
Southeast winds near 5 knots. Seas around 1 foot. Nearshore waters smooth.

---

GMZ052>055-072>075-220230
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
1029 AM EDT Tue Jul 21 2026

THIS AFTERNOON
Southeast winds near 15 knots, becoming east to southeast and decreasing to near 10 knots. Seas 2 to 4 feet, occasionally to 5 feet, subsiding to 2 to 3 feet. Wave Detail: East to southeast 3 feet at 5 seconds and west 2 feet at 6 seconds.

TONIGHT
East to southeast winds 10 to 15 knots, increasing to near 15 knots. Seas 2 to 4 feet, occasionally to 5 feet. Wave Detail: East to southeast 3 feet at 5 seconds and west 2 feet at 6 seconds. A slight chance of showers and thunderstorms.

WEDNESDAY
East to southeast winds near 15 knots, decreasing to 10 to 15 knots. Seas 2 to 4 feet, occasionally to 5 feet. Wave Detail: East to southeast 3 feet at 5 seconds and west 2 feet at 7 seconds. A slight chance of showers and thunderstorms.

WEDNESDAY NIGHT
East winds 10 to 15 knots. Seas 2 to 4 feet, occasionally to 5 feet. A slight chance of showers and thunderstorms.

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

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

FRIDAY
East winds near 10 knots, decreasing to 5 to 10 knots. Seas 2 to 3 feet, subsiding to 1 to 2 feet. A chance of showers and thunderstorms.

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

SATURDAY
Southeast winds 5 to 10 knots. Seas 1 to 2 feet.

SATURDAY NIGHT
East to southeast winds near 5 knots. Seas around 1 foot.

---

GMZ033-034-220230
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
1029 AM EDT Tue Jul 21 2026

THIS AFTERNOON
Southeast to south winds near 15 knots, becoming southeast and decreasing to near 10 knots. Seas 2 to 3 feet. Wave Detail: Southeast to south 3 feet at 4 seconds and west 2 feet at 6 seconds.

TONIGHT
Southeast winds 5 to 10 knots, increasing to near 15 knots after midnight. Seas 2 to 3 feet. Wave Detail: West to northwest 3 feet at 7 seconds and southeast 2 feet at 4 seconds.

WEDNESDAY
Southeast winds 10 to 15 knots, decreasing to near 10 knots. Seas 2 to 3 feet. Wave Detail: Southeast 2 feet at 4 seconds and west 2 feet at 6 seconds. A slight chance of showers and thunderstorms.

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

THURSDAY
East winds near 10 knots, decreasing to 5 to 10 knots. Seas 2 to 3 feet. A slight chance of showers and thunderstorms.

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

SATURDAY
Southeast to south winds near 5 knots. Seas around 1 foot.

SATURDAY NIGHT
North to northeast winds near 5 knots, becoming south after midnight. Seas around 1 foot.