899
FZUS52 KKEY 210820
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
420 AM EDT Fri Aug 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.

GMZ005-212030-
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas
420 AM EDT Fri Aug 21 2026

.SYNOPSIS...
A split ridge pattern remains in place across the Florida Keys
coastal waters. This will promote generally light to gentle SE
breezes today, becoming variable at times during the afternoon, with
a chance for thunderstorms in the southeastern Gulf. SE breezes
will become more established over the weekend, freshening and
becoming gentle to moderate at times during the overnight hours as
Atlantic ridging builds slightly westward across the Bahamas.
Rain chances will also slightly increase across the coastal waters
this weekend in response to rising moisture content and subsiding
SAL dust concentrations.

The Approximate Shoreward Edge of the Gulf Stream as of August
19, 2026...

37 NM south of Dry Tortugas Light, on Loggerhead Key
20 NM south-southeast of Cosgrove Shoal Light, off the Marquesas Keys
14 NM south-southeast of Sand Key Light, off Key West
10 NM south-southeast of Looe Key, off Big Pine Key
10 NM south-southeast of Sombrero Key Light, off Marathon
 3 NM southeast of Alligator Reef Light, off Islamorada
 1 NM west-northwest of Molasses Reef Light, off Key Largo
 1 NM east-southeast of Carysfort Reef Light, off Ocean Reef

Gulf Stream Information Courtesy of the Naval Oceanographic
Office.

$$

GMZ031-212030-
Florida Bay including Barnes Sound, Blackwater Sound, and
Buttonwood Sound-
420 AM EDT Fri Aug 21 2026

.TODAY...Southeast to south winds near 5 knots. Bay waters
smooth. A slight chance of showers and thunderstorms.
.TONIGHT...Southeast winds 5 to 10 knots. Bay waters smooth to a
light chop.
.SATURDAY...Southeast winds near 5 knots. Bay waters smooth. A
chance of showers and thunderstorms.
.SATURDAY NIGHT...Southeast winds 5 to 10 knots. Bay waters
smooth to a light chop. A slight chance of showers and
thunderstorms.
.SUNDAY...Southeast winds 5 to 10 knots. Bay waters smooth to a
light chop. A chance of showers and thunderstorms.
.SUNDAY NIGHT...Southeast winds 5 to 10 knots. Bay waters smooth
to a light chop. A chance of showers and thunderstorms.
.MONDAY...East winds near 5 knots, becoming 5 to 10 knots. Bay
waters smooth, becoming a smooth to light chop. A slight chance
of showers and thunderstorms.
.MONDAY NIGHT...East winds 5 to 10 knots. Bay waters smooth to a
light chop. A chance of showers and thunderstorms.
.TUESDAY...East to southeast winds 5 to 10 knots. Bay waters
smooth to a light chop. A chance of showers and thunderstorms.
.TUESDAY NIGHT...East winds near 10 knots. Bay waters a light
chop. A chance of showers and thunderstorms.

$$

GMZ032-035-212030-
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-
420 AM EDT Fri Aug 21 2026

.TODAY...Southeast to south winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.TONIGHT...Southeast winds 5 to 10 knots. Seas 1 foot or less.
Nearshore waters smooth to a light chop.
.SATURDAY...Southeast winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.SATURDAY NIGHT...Southeast winds near 5 knots, increasing to
5 to 10 knots. Seas 1 foot or less. Nearshore waters smooth,
becoming smooth to a light chop. A slight chance of showers and
thunderstorms.
.SUNDAY...Southeast winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.SUNDAY NIGHT...Southeast winds 5 to 10 knots. Seas 1 foot or
less. Nearshore waters smooth to a light chop. A chance of
showers and thunderstorms.
.MONDAY...East to southeast winds 5 to 10 knots. Seas 1 foot or
less. Nearshore waters smooth to a light chop. A slight chance of
showers and thunderstorms.
.MONDAY NIGHT...East winds 5 to 10 knots. Seas 1 foot or less.
Nearshore waters smooth to a light chop. A chance of showers and
thunderstorms.
.TUESDAY...East to southeast winds near 10 knots. Seas around 1
foot. Nearshore waters a light chop. A slight chance of showers
and thunderstorms.
.TUESDAY NIGHT...East to southeast winds near 10 knots. Seas
around 1 foot. Nearshore waters a light chop. Showers and
thunderstorms likely.

$$

GMZ042>044-212030-
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 Fri Aug 21 2026

.TODAY...Southeast to south winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.TONIGHT...East to southeast winds 5 to 10 knots. Seas around 1
foot. Nearshore waters smooth to a light chop.
.SATURDAY...East to southeast winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A chance of showers and
thunderstorms.
.SATURDAY 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 and thunderstorms.
.SUNDAY...East to southeast winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.SUNDAY 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 and thunderstorms.
.MONDAY...East winds 5 to 10 knots. Seas around 1 foot. Nearshore
waters smooth to a light chop.
.MONDAY NIGHT...East winds near 10 knots. Seas 1 to 2 feet.
Nearshore waters a light chop. A chance of showers and
thunderstorms.
.TUESDAY...East winds near 10 knots. Seas 1 to 2 feet. Nearshore
waters a light chop. A slight chance of showers and thunderstorms.
.TUESDAY NIGHT...East winds 10 to 15 knots. Seas 1 to 3 feet.
Nearshore waters a light to moderate chop. A chance of showers and
thunderstorms.

$$

GMZ052>055-072>075-212030-
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 Fri Aug 21 2026

.TODAY...Southeast winds 5 to 10 knots, becoming east. Seas 1 to 2
feet. Wave Detail: East to southeast 1 foot at 3 seconds. A
slight chance of showers and thunderstorms.
.TONIGHT...East to southeast winds 5 to 10 knots. Seas 1 to 2 feet.
Wave Detail: East 1 foot at 4 seconds.
.SATURDAY...East to southeast winds near 5 knots. Seas around
1 foot. Wave Detail: East to southeast 1 foot at 3 seconds. A
slight chance of showers and thunderstorms.
.SATURDAY NIGHT...East to southeast winds 5 to 10 knots. Seas
1 to 2 feet. A slight chance of showers and thunderstorms.
.SUNDAY...East to southeast winds 5 to 10 knots. Seas 1 to 2 feet.
A slight chance of showers and thunderstorms.
.SUNDAY NIGHT...East to southeast winds 5 to 10 knots. Seas 1 to
2 feet. A chance of showers and thunderstorms.
.MONDAY...East winds near 10 knots. Seas 1 to 3 feet.
.MONDAY NIGHT...East winds near 10 knots. Seas 1 to 3 feet. A
chance of showers and thunderstorms.
.TUESDAY...East winds near 10 knots. Seas 1 to 3 feet. A slight
chance of showers and thunderstorms.
.TUESDAY NIGHT...East winds 10 to 15 knots. Seas 2 to 4 feet,
occasional 5 feet. A chance of showers and thunderstorms.

$$

GMZ033-034-212030-
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 Fri Aug 21 2026

.TODAY...Southwest winds near 5 knots, becoming variable. Seas
1 foot or less. Wave Detail: Northwest 1 foot at 5 seconds. A
chance of showers and thunderstorms.
.TONIGHT...Variable near 5 knots, becoming southeast 5 to 10
knots. Seas 1 foot or less, building to around 1 foot. Wave
Detail: Northwest 1 foot at 4 seconds. A slight chance of showers
and thunderstorms.
.SATURDAY...Southeast to south winds near 5 knots, becoming
variable. Seas 1 foot or less. Wave Detail: Northwest 1 foot at 4
seconds. A slight chance of showers and thunderstorms.
.SATURDAY NIGHT...Variable near 5 knots, becoming southeast. Seas
1 foot or less.
.SUNDAY...Variable near 5 knots. Seas 1 foot or less. A slight
chance of showers and thunderstorms.
.SUNDAY NIGHT...East to southeast winds near 5 knots. Seas 1 foot
or less. A slight chance of showers and thunderstorms.
.MONDAY...East winds 5 to 10 knots. Seas around 1 foot. A slight
chance of showers and thunderstorms.
.MONDAY NIGHT...East to southeast winds 5 to 10 knots. Seas
around 1 foot. A chance of showers and thunderstorms.
.TUESDAY...East to southeast winds 5 to 10 knots. Seas around 1
foot. A chance of showers and thunderstorms.
.TUESDAY NIGHT...East winds near 10 knots. Seas 1 to 2 feet.
Showers and thunderstorms likely.

$$