HomeForecastsFlorida ForecastsJohnson Keys, FL - South End Coastal Forecast

Johnson Keys, FL - South End Coastal Forecast

FZUS52 KKEY 211436
CWFKEY

Coastal Waters Forecast for the Florida Keys
National Weather Service Key West FL
1036 AM EDT Mon Apr 21 2025

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.

GMZ005-212045-
Synopsis for Keys coastal waters from Ocean Reef to Dry Tortugas
1036 AM EDT Mon Apr 21 2025

.SYNOPSIS...Fresh to occasionally strong easterlies, mainly in the
Straits of Florida, will modestly slacken this afternoon as high
pressure weakens slightly. Even though the high weakens slightly
today, expect this high to continue to meander for the next
several days north of The Bahamas leading to peaking winds and
night and lulling during the day. Another surge in northeast to
east breezes is possible Thursday into the weekend as the high
strengthens and drifts back westward.

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

30 NM South of Dry Tortugas Light...on Loggerhead Key.
8 NM South of Cosgrove Shoal Light...off the Marquesas Keys.
5 NM South of Sand Key Light...off Key West.
9 NM South of Looe Key...off Big Pine Key.
13 NM South of Sombrero Key Light...off Marathon.
15 NM Southeast of Alligator Reef Light...off Islamorada.
14 NM Southeast of Molasses Reef Light...off Key Largo.
12 NM East 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.

$$

GMZ031-212045-
Florida Bay including Barnes Sound, Blackwater Sound, and
Buttonwood Sound-
1036 AM EDT Mon Apr 21 2025

...SMALL CRAFT SHOULD EXERCISE CAUTION...

.THIS AFTERNOON...East winds 15 to 20 knots. Bay waters choppy.
.TONIGHT...East winds 15 to 20 knots. Bay waters choppy.
.TUESDAY...East winds near 15 knots. Bay waters a moderate chop.
.TUESDAY NIGHT...East winds 15 to 20 knots. Bay waters choppy.
.WEDNESDAY...East winds near 15 knots. Bay waters a moderate
chop.
.WEDNESDAY NIGHT...Northeast to east winds 15 to 20 knots. Bay
waters choppy.
.THURSDAY...East winds 15 to 20 knots, increasing to near 20 knots.
Bay waters choppy, becoming rough. Isolated showers.
.THURSDAY NIGHT...East winds near 20 knots. Bay waters rough.
Isolated showers.
.FRIDAY...East winds near 20 knots. Bay waters rough. Isolated
showers.
.FRIDAY NIGHT...Northeast to east winds 15 to 20 knots. Bay
waters choppy. Isolated showers.

$$

GMZ032-035-212045-
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-
1036 AM EDT Mon Apr 21 2025

...SMALL CRAFT SHOULD EXERCISE CAUTION...

.THIS AFTERNOON...East winds 15 to 20 knots. Seas 2 to 3 feet,
subsiding to 1 to 2 feet. West of the Marquesas Keys, seas 3 to 5
feet, occasionally to 6 feet, subsiding to 3 to 4 feet,
occasionally to 5 feet. Nearshore waters choppy.
.TONIGHT...East winds 15 to 20 knots. Seas 1 to 3 feet, except 3
to 4 feet, occasionally to 5 feet west of the Marquesas Keys.
Nearshore waters choppy.
.TUESDAY...East to southeast winds 15 to 20 knots, decreasing to
near 15 knots in the afternoon. Seas 1 to 3 feet, subsiding to 1
to 2 feet. West of the Marquesas Keys, seas 3 to 4 feet,
occasionally to 5 feet, subsiding to 2 to 3 feet. Nearshore waters
choppy, becoming a moderate chop.
.TUESDAY NIGHT...East winds 15 to 20 knots. Seas 1 to 2 feet,
except around 3 feet west of the Marquesas Keys. Nearshore waters
choppy.
.WEDNESDAY...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.
.WEDNESDAY NIGHT...Northeast to east winds 15 to 20 knots. Seas 1
to 3 feet, except around 3 feet west of the Marquesas Keys.
Nearshore waters choppy.
.THURSDAY...East winds 15 to 20 knots, increasing to near 20
knots. Seas 2 to 3 feet, except 3 to 4 feet, occasionally to 5
feet west of the Marquesas Keys. Nearshore waters choppy, becoming
rough. Isolated showers.
.THURSDAY NIGHT...East winds near 20 knots. Seas 2 to 3 feet,
except around 4 feet, occasionally to 5 feet west of the
Marquesas Keys. Nearshore waters rough. Isolated showers.
.FRIDAY...East winds near 20 knots. Seas 2 to 3 feet, except 3 to
4 feet, occasionally to 5 feet west of the Marquesas Keys.
Nearshore waters rough. Isolated showers.
.FRIDAY NIGHT...East winds near 20 knots. Seas 2 to 3 feet,
except around 4 feet, occasionally to 5 feet west of the
Marquesas Keys. Nearshore waters rough. Isolated showers.

$$

GMZ042>044-212045-
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-
1036 AM EDT Mon Apr 21 2025

...SMALL CRAFT SHOULD EXERCISE CAUTION...

.THIS AFTERNOON...East winds 15 to 20 knots. Seas 3 to 5 feet,
occasionally to 6 feet. Nearshore waters choppy.
.TONIGHT...East winds 15 to 20 knots. Seas 3 to 5 feet,
occasionally to 6 feet. Nearshore waters choppy.
.TUESDAY...East winds 15 to 20 knots, decreasing to near 15 knots
in the afternoon. Seas 2 to 4 feet, occasionally to 5 feet.
Nearshore waters choppy, becoming a moderate chop.
.TUESDAY NIGHT...East winds 15 to 20 knots. Seas 2 to 4 feet,
occasionally to 5 feet. Nearshore waters choppy.
.WEDNESDAY...East winds near 15 knots. Seas 2 to 4 feet,
occasionally to 5 feet. Nearshore waters a moderate chop.
.WEDNESDAY NIGHT...Northeast to east winds 15 to 20 knots. Seas 2
to 4 feet, occasionally to 5 feet. Nearshore waters choppy.
.THURSDAY...Northeast to east winds 15 to 20 knots, increasing to
near 20 knots. Seas 2 to 4 feet, occasionally to 5 feet.
Nearshore waters choppy, becoming rough. Isolated showers.
.THURSDAY NIGHT THROUGH FRIDAY NIGHT...East winds near 20 knots.
Seas 3 to 5 feet, occasionally to 6 feet. Nearshore waters rough.
Isolated showers.

$$

GMZ052>055-072>075-212045-
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-
1036 AM EDT Mon Apr 21 2025

...SMALL CRAFT ADVISORY IN EFFECT...

.THIS AFTERNOON...East winds 20 to 25 knots, decreasing to 15 to
20 knots. Seas 5 to 8 feet, occasionally to 10 feet, subsiding to
4 to 7 feet, occasionally to 9 feet. Wave Detail: East 6 feet at
7 seconds.
.TONIGHT...East winds 15 to 20 knots. Seas 4 to 7 feet,
occasionally to 9 feet. Wave Detail: East 5 feet at 6 seconds.
.TUESDAY...East to southeast winds 15 to 20 knots. Seas 4 to 6
feet, occasionally to 8 feet. Wave Detail: East to southeast 5
feet at 6 seconds.
.TUESDAY NIGHT...East winds 15 to 20 knots. Seas 4 to 6 feet,
occasionally to 8 feet.
.WEDNESDAY...East winds 15 to 20 knots. Seas 3 to 5 feet,
occasionally to 6 feet.
.WEDNESDAY NIGHT...Northeast to east winds 15 to 20 knots. Seas
4 to 6 feet, occasionally to 8 feet. Isolated showers.
.THURSDAY...Northeast to east winds 15 to 20 knots, increasing to
near 20 knots. Seas 5 to 6 feet, occasionally to 8 feet. Isolated
showers.
.THURSDAY NIGHT...Northeast to east winds 20 to 25 knots, becoming
east. Seas 6 to 8 feet, occasionally to 10 feet. Isolated
showers.
.FRIDAY...East winds near 20 knots. Seas 5 to 7 feet,
occasionally to 9 feet. Isolated showers.
.FRIDAY NIGHT...Northeast to east winds near 20 knots. Seas 5 to
7 feet, occasionally to 9 feet. Isolated showers.

$$

GMZ033-034-212045-
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-
1036 AM EDT Mon Apr 21 2025

...SMALL CRAFT SHOULD EXERCISE CAUTION...

.THIS AFTERNOON...East to southeast winds 15 to 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. Wave
Detail: East 4 feet at 5 seconds.
.TONIGHT...East to southeast winds increasing to 15 to 20 knots.
Seas building to 3 to 5 feet, occasionally to 6 feet. Wave
Detail: East to southeast 4 feet at 4 seconds.
.TUESDAY...East to southeast winds 15 to 20 knots, decreasing to
10 to 15 knots in the afternoon. Seas 2 to 4 feet, occasionally
to 5 feet, subsiding to 2 to 3 feet. Wave Detail: East to
southeast 3 feet at 4 seconds.
.TUESDAY NIGHT...East winds 10 to 15 knots, increasing to near 15
knots. Seas 2 to 3 feet, building to 2 to 4 feet, occasionally to
5 feet.
.WEDNESDAY...East to southeast winds near 15 knots. Seas 2 to 4
feet, occasionally to 5 feet.
.WEDNESDAY NIGHT...East to southeast winds near 15 knots,
increasing to 15 to 20 knots. Seas 2 to 4 feet, occasionally to 5
feet, building to 3 to 4 feet, occasionally to 4 feet.
.THURSDAY...East winds 15 to 20 knots. Seas 3 to 4 feet,
occasionally to 5 feet.
.THURSDAY NIGHT...East winds near 20 knots. Seas 3 to 5 feet,
occasionally to 6 feet. Isolated showers.
.FRIDAY AND FRIDAY NIGHT...East winds 15 to 20 knots. Seas 3 to 5
feet, occasionally to 6 feet.

$$

AP/MJV


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