487
FZUS52 KKEY 182027
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
427 PM EDT Tue Aug 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.

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.

GMZ005-190830-
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas
427 PM EDT Tue Aug 18 2026

.SYNOPSIS...
A pressure axis draped across the Florida Keys will maintain a
mostly variable wind pattern this week with wind speeds mainly
less than 10 knots. However, brief surges in wind speeds are
possible in the late afternoon and evening hours with winds
occasionally approaching 15 to 20 knots, mostly near the Upper
Keys, so marine caution headlines are in place for the waters
adjacent to the Upper Keys. In addition, the presence of Saharan
air across the area will keep near zero rain chances through the
middle of the week with a very small increase in rain chances by
the end of the week as moisture slowly recovers. The best rain
chances late in the week will typically occur north of the Island
Chain in the Bay and Gulf side waters, though any activity in
general is expected to be isolated to scattered in nature.

The Approximate Shoreward Edge of the Gulf Stream as of August
13, 2026...

38 NM South of Dry Tortugas Light...on Loggerhead Key.
20 NM South of Cosgrove Shoal Light...off the Marquesas Keys.
17 NM South of Sand Key Light...off Key West.
21 NM South of Looe Key...off Big Pine Key.
18 NM Southeast of Sombrero Key Light...off Marathon.
 7 NM Southeast of Alligator Reef Light...off Islamorada.
 7 NM Southeast of Molasses Reef Light...off Key Largo.
 2 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.

$$

GMZ031-190830-
Florida Bay including Barnes Sound, Blackwater Sound, and
Buttonwood Sound-
427 PM EDT Tue Aug 18 2026

...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL WINDS DECREASE...

.TONIGHT...West to northwest winds 15 to 20 knots early, becoming
northwest and decreasing to near 10 knots. Bay waters choppy,
becoming a light chop.
.WEDNESDAY...Northwest winds near 10 knots early, becoming
southwest to west and decreasing to 5 to 10 knots. Bay waters
a light chop, becoming smooth to a light chop.
.WEDNESDAY NIGHT...West to northwest winds 5 to 10 knots. Bay
waters smooth to a light chop. A slight chance of showers and
thunderstorms.
.THURSDAY...West winds 5 to 10 knots, becoming southwest to west.
Bay waters smooth to a light chop. A slight chance of showers and
thunderstorms.
.THURSDAY NIGHT...Southwest winds near 5 knots, becoming
southeast to south. Bay waters smooth. A slight chance of showers
and thunderstorms.
.FRIDAY...South to southwest winds near 5 knots. Bay waters
smooth. A slight chance of showers and thunderstorms.
.FRIDAY NIGHT...Southeast to south winds near 5 knots. Bay waters
smooth. A slight chance of showers.
.SATURDAY...South winds near 5 knots. Bay waters smooth. A slight
chance of showers and thunderstorms.
.SATURDAY NIGHT...Southeast winds near 5 knots. Bay waters
smooth. A slight chance of showers.
.SUNDAY...Southeast to south winds near 5 knots. Bay waters
smooth. A slight chance of showers and thunderstorms.
.SUNDAY NIGHT...Southeast winds near 5 knots. Bay waters smooth.
A slight chance of showers.

$$

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-
427 PM EDT Tue Aug 18 2026

.TONIGHT...Northwest to north winds 10 to 15 knots early,
becoming northwest and decreasing to near 10 knots. Seas 1 foot or
less. Nearshore waters a light to moderate chop, becoming a light
chop late.
.WEDNESDAY...Northwest winds 5 to 10 knots, increasing to near 10
knots. Seas 1 foot or less. Nearshore waters smooth to a light
chop, becoming a light chop.
.WEDNESDAY NIGHT...Northwest winds 10 to 15 knots, becoming 5 to
10 knots. Seas around 1 foot. Nearshore waters a light to
moderate chop, becoming smooth to a light chop. A slight chance of
showers and thunderstorms.
.THURSDAY...Northwest to west winds near 5 knots, becoming west.
Seas 1 foot or less. Nearshore waters smooth. A slight chance of
showers and thunderstorms.
.THURSDAY NIGHT...West winds near 5 knots, becoming southeast to
south. Seas 1 foot or less. Nearshore waters smooth. A slight
chance of showers and thunderstorms.
.FRIDAY...South to southwest winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth.
.FRIDAY NIGHT...Southeast winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers.
.SATURDAY...South winds near 5 knots, becoming southeast. Seas 1
foot or less. Nearshore waters smooth. A slight chance of showers
and thunderstorms.
.SATURDAY NIGHT THROUGH SUNDAY NIGHT...Southeast winds near 5
knots. Seas 1 foot or less. Nearshore waters smooth. A slight
chance of showers and thunderstorms.

$$

GMZ042-190830-
Hawk Channel from Ocean Reef to Craig Key out to the reef-
427 PM EDT Tue Aug 18 2026

...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL WINDS DECREASE...

.TONIGHT...Northwest winds 15 to 20 knots early, decreasing to 10
to 15 knots. Seas around 1 foot. Nearshore waters choppy, becoming
a light to moderate chop.
.WEDNESDAY...West to northwest winds 5 to 10 knots, becoming
southwest. Seas 1 foot or less. Nearshore waters smooth to a
light chop.
.WEDNESDAY NIGHT...Northwest winds 5 to 10 knots. Seas around 1
foot. Nearshore waters smooth to a light chop.
.THURSDAY...West winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.THURSDAY NIGHT...West winds near 5 knots, becoming southeast to
south after midnight. Seas 1 foot or less. Nearshore waters
smooth, becoming smooth to a light chop.
.FRIDAY...South winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth.
.FRIDAY NIGHT...Southeast winds near 5 knots. Seas around 1 foot.
Nearshore waters smooth.
.SATURDAY...Southeast to south winds near 5 knots. Seas around
1 foot. Nearshore waters smooth. A slight chance of showers.
.SATURDAY NIGHT...East to southeast winds near 5 knots. Seas
around 1 foot. Nearshore waters smooth. A slight chance of
showers.
.SUNDAY...Southeast to south winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.SUNDAY NIGHT...Southeast winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers.

$$

GMZ043-044-190830-
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-
427 PM EDT Tue Aug 18 2026

.TONIGHT...Northwest to north winds near 10 knots, decreasing to 5
to 10 knots. Seas around 1 foot. Nearshore waters a light chop,
becoming smooth to a light chop.
.WEDNESDAY...Northwest winds 5 to 10 knots. Seas around 1 foot.
Nearshore waters smooth to a light chop.
.WEDNESDAY NIGHT...Northwest winds 5 to 10 knots. Seas around 1
foot. Nearshore waters smooth to a light chop.
.THURSDAY...West winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth. A slight chance of showers and
thunderstorms.
.THURSDAY NIGHT...West winds near 5 knots, becoming southeast to
south. Seas 1 foot or less. Nearshore waters smooth.
.FRIDAY...South winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth.
.FRIDAY NIGHT...Southeast winds near 5 knots. Seas around 1 foot.
Nearshore waters smooth.
.SATURDAY...Southeast to south winds near 5 knots. Seas around
1 foot. Nearshore waters smooth. A slight chance of showers.
.SATURDAY NIGHT...East to southeast winds near 5 knots. Seas
around 1 foot. Nearshore waters smooth. A slight chance of
showers.
.SUNDAY...East to southeast winds near 5 knots. Seas 1 foot or
less. Nearshore waters smooth. A slight chance of showers.
.SUNDAY NIGHT...East winds near 5 knots. Seas 1 foot or less.
Nearshore waters smooth. A slight chance of showers.

$$

GMZ052-072-190830-
Straits of Florida from Ocean Reef to Craig Key out 20 NM-
Straits of Florida from Ocean Reef to Craig Key 20 to 60 NM out-
427 PM EDT Tue Aug 18 2026

...SMALL CRAFT SHOULD EXERCISE CAUTION UNTIL WINDS DECREASE...

.TONIGHT...Northwest winds 15 to 20 knots early, becoming
northwest and decreasing to near 10 knots. Seas around 1 foot.
Wave Detail: West 1 foot at 2 seconds and southeast 1 foot at 3
seconds.
.WEDNESDAY...West to northwest winds near 10 knots early,
decreasing to 5 to 10 knots. Seas 1 foot or less. Wave Detail:
Northwest 1 foot at 3 seconds.
.WEDNESDAY NIGHT...Southwest to west winds 5 to 10 knots,
becoming south. Seas 1 foot or less. Wave Detail: West 1 foot at 2
seconds.
.THURSDAY...South to southwest winds near 5 knots. Seas 1 foot or
less.
.THURSDAY NIGHT...South winds near 5 knots, becoming southeast to
south. Seas 1 foot or less.
.FRIDAY...Southeast to south winds near 5 knots. Seas around 1
foot.
.FRIDAY NIGHT...Southeast winds 5 to 10 knots. Seas around 1
foot. A slight chance of showers and thunderstorms.
.SATURDAY...Southeast winds near 5 knots. Seas around 1 foot.
.SATURDAY NIGHT...Southeast winds 5 to 10 knots. Seas around 1
foot. A slight chance of showers and thunderstorms.
.SUNDAY...Southeast winds 5 to 10 knots. Seas 1 foot or less. A
slight chance of showers.
.SUNDAY NIGHT...East to southeast winds 5 to 10 knots. Seas 1
foot or less. A slight chance of showers.

$$

GMZ053>055-073>075-190830-
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 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-
427 PM EDT Tue Aug 18 2026

.TONIGHT...North winds near 10 knots, becoming northwest and
decreasing to 5 to 10 knots. Seas around 1 foot. Wave Detail:
Northeast to east 1 foot at 4 seconds.
.WEDNESDAY...Northwest to north winds near 5 knots. Seas 1 foot
or less. Wave Detail: North 1 foot at 3 seconds.
.WEDNESDAY NIGHT...Northwest to north winds 5 to 10 knots. Seas
1 foot or less. Wave Detail: Northwest to north 1 foot at 3
seconds.
.THURSDAY...North winds near 5 knots. Seas 1 foot or less.
.THURSDAY NIGHT...Northeast to east winds 5 to 10 knots, becoming
east to southeast. Seas 1 foot or less.
.FRIDAY...East to southeast winds near 5 knots. Seas around 1
foot.
.FRIDAY NIGHT...Northeast to east winds 5 to 10 knots, becoming
east to southeast. Seas around 1 foot.
.SATURDAY...East to southeast winds near 5 knots. Seas around
1 foot.
.SATURDAY NIGHT...East winds near 5 knots. Seas around 1 foot.
.SUNDAY...East winds near 5 knots. Seas 1 foot or less.
.SUNDAY NIGHT...East winds 5 to 10 knots. Seas 1 foot or less.

$$

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-
427 PM EDT Tue Aug 18 2026

.TONIGHT...Northwest winds near 10 knots, decreasing to 5 to 10
knots. Seas around 1 foot. Wave Detail: Northwest to north 1 foot
at 3 seconds.
.WEDNESDAY...Northwest winds 5 to 10 knots. Seas 1 to 2 feet.
Wave Detail: Northwest to north 1 foot at 4 seconds.
.WEDNESDAY NIGHT...Northwest winds 5 to 10 knots. Seas 1 to
2 feet. Wave Detail: Northwest 2 feet at 5 seconds. A slight
chance of showers and thunderstorms.
.THURSDAY...Northwest winds 5 to 10 knots. Seas around 1 foot. A
slight chance of showers and thunderstorms.
.THURSDAY NIGHT...West to northwest winds 5 to 10 knots, becoming
south. Seas around 1 foot. A slight chance of showers and
thunderstorms.
.FRIDAY...Southwest to west winds near 5 knots. Seas around
1 foot.
.FRIDAY NIGHT...Northeast winds near 5 knots, becoming variable.
Seas around 1 foot. A slight chance of showers and thunderstorms.
.SATURDAY...Southwest winds near 5 knots. Seas around 1 foot. A
slight chance of showers.
.SATURDAY NIGHT...Variable winds near 5 knots. Seas around 1
foot. A slight chance of showers.
.SUNDAY...Variable winds near 5 knots, becoming northwest to
north. Seas 1 foot or less. A slight chance of showers.
.SUNDAY NIGHT...Northeast to east winds near 5 knots. Seas 1 foot
or less. A slight chance of showers and thunderstorms.

$$