Guide
Small craft advisories on Florida’s Gulf coast
Checked October 4, 2026 against the National Weather Service offices in Mobile, Tallahassee, Tampa Bay, Miami, Jacksonville, Melbourne and Key West and the National Weather Service’s marine definitions.
The Marine tile repeats the National Weather Service’s coastal waters forecast for the water your town opens onto. On this coast that may be the Gulf, a bay, Santa Rosa Sound, Tampa Bay or Charlotte Harbor, and each is forecast separately, by one of four offices. This page explains which zone each town reads, how a bay forecast differs from a Gulf one, and what the advisories and warnings mean in knots and feet.
Four offices, from Perdido Key to Chokoloskee
The weather service office in Mobile writes the coastal waters forecast from Pensacola to the Okaloosa–Walton county line, and its bays as far as Choctawhatchee Bay. The office in Tallahassee writes it from that line east and around the Big Bend to the mouth of the Suwannee River, updated several times a day. The office in Tampa Bay (it sits in Ruskin) writes it from the Suwannee south to Bonita Beach, and says its forecasts are issued at least four times a day. The office in Miami writes the Gulf from Bonita Beach south past Chokoloskee, about twice a day. The Gulf is a strip out 20 nautical miles from shore with a second zone from 20 to 60 beyond it, and each bay with a zone of its own is listed. The names below are the weather service’s own, by stretch, north and west first.
Pensacola to Destin
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ650 | Coastal waters from Pensacola FL to Pascagoula MS out 20 NM | Mobile | Perdido Key |
| GMZ634 | Pensacola Bay Area including Santa Rosa Sound | Mobile | Pensacola, Gulf Breeze, Fort Walton Beach |
| GMZ655 | Coastal waters from Okaloosa-Walton County Line to Pensacola FL out 20 NM | Mobile | Pensacola Beach, Navarre, Okaloosa Island |
| GMZ635 | Western Choctawhatchee Bay | Mobile | Destin, Niceville |
Walton and Bay counties
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ636 | Eastern Choctawhatchee Bay | Mobile | Freeport, Santa Rosa Beach |
| GMZ751 | Coastal waters from Okaloosa-Walton County Line to Mexico Beach out 20 NM | Tallahassee | Grayton Beach, Rosemary Beach, Panama City Beach, Mexico Beach |
| GMZ735 | St. Andrews Bay Waterways | Tallahassee | Panama City, Lynn Haven |
The Forgotten Coast and the Big Bend
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ752 | Coastal Waters from Mexico Beach to Apalachicola out 20 NM | Tallahassee | Port St. Joe, Cape San Blas |
| GMZ755 | Coastal Waters From Ochlockonee River to Apalachicola FL out to 20 NM | Tallahassee | Apalachicola, Eastpoint, St. George Island, Carrabelle, Alligator Point |
| GMZ730 | Apalachee Bay or Coastal Waters From Keaton Beach to Ochlockonee River FL out to 20 NM | Tallahassee | St. Marks, Shell Point, Panacea |
| GMZ765 | Coastal waters from Suwannee River to Keaton Beach out 20 NM | Tallahassee | Keaton Beach, Steinhatchee, Horseshoe Beach, Suwannee |
The Nature Coast
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ850 | Coastal waters from Tarpon Springs to Suwannee River FL out 20 NM | Tampa Bay | Cedar Key, Yankeetown, Crystal River, Homosassa, Hernando Beach, Hudson, Port Richey, New Port Richey |
Tampa Bay
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ853 | Coastal waters from Englewood to Tarpon Springs FL out 20 NM | Tampa Bay | Tarpon Springs, Dunedin, Clearwater Beach, Clearwater, Indian Rocks Beach, Madeira Beach, Treasure Island, St. Pete Beach, Anna Maria, Holmes Beach |
| GMZ830 | Tampa Bay waters | Tampa Bay | Gulfport, St. Petersburg, Tampa, Apollo Beach, Ruskin, Palmetto, Bradenton |
Sarasota to Bonita Springs
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ853 (the same zone) | Coastal waters from Englewood to Tarpon Springs FL out 20 NM | Tampa Bay | Longboat Key, Sarasota, Siesta Key, Venice, Englewood |
| GMZ836 | Charlotte Harbor and Pine Island Sound | Tampa Bay | Port Charlotte, Punta Gorda, Placida, Bokeelia, Matlacha, Cape Coral |
| GMZ856 | Coastal waters from Bonita Beach to Englewood FL out 20 NM | Tampa Bay | Boca Grande, Fort Myers, Captiva, Sanibel, Fort Myers Beach, Bonita Springs |
Collier County
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ656 | Coastal waters from Chokoloskee to Bonita Beach FL out 20 NM | Miami | Naples, Marco Island, Goodland, Everglades City, Chokoloskee |
Perdido Bay, behind Perdido Key, is GMZ633; no town on this coast reads it. Sarasota Bay, the Caloosahatchee and the bays behind Naples and Marco Island have no zone of their own, so the towns on them read the Gulf zone off their beaches. Beyond the 20-mile line are the 20-to-60-mile zones of each office.
The Atlantic coast and the Keys
Four more offices write the water on the other side of the state. Jacksonville writes the Atlantic from the Georgia line to Flagler Beach, its three nearshore zones in one forecast, about every six hours. Melbourne writes it from Flagler Beach to Jupiter Inlet, zone by zone, about every six hours. Miami writes Jupiter Inlet to Ocean Reef and Biscayne Bay, the one bay on the Atlantic with a zone of its own, about twice a day. Key West writes the Keys every six hours: Hawk Channel inside the reef, Florida Bay and the Gulf side behind the islands, and the Straits of Florida outside the reef. Every Keys town sits within a mile or so of all three, so the Keys board reads Hawk Channel first, the bay second and the Straits third. Jacksonville, eleven miles up the St. Johns, reads the ocean off its own beaches. The Indian River Lagoon, the Halifax, the Matanzas and the Intracoastal have no zone of their own.
The First Coast
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| AMZ452 | Coastal waters from Fernandina Beach to St. Augustine FL out 20 NM | Jacksonville | Fernandina Beach, Mayport, Jacksonville, Atlantic Beach, Neptune Beach, Jacksonville Beach, Ponte Vedra Beach, Vilano Beach |
| AMZ454 | Coastal waters from St. Augustine to Flagler Beach FL out 20 NM | Jacksonville | St. Augustine, St. Augustine Beach, Crescent Beach, Palm Coast, Flagler Beach |
The Space Coast
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| AMZ550 | Flagler Beach to Volusia-Brevard County Line 0-20 nm | Melbourne | Ormond Beach, Daytona Beach, Daytona Beach Shores, Port Orange, Ponce Inlet, New Smyrna Beach, Edgewater, Oak Hill |
| AMZ552 | Volusia-Brevard County Line to Sebastian Inlet 0-20 nm | Melbourne | Titusville, Merritt Island, Cape Canaveral, Cocoa, Rockledge, Cocoa Beach, Satellite Beach, Indian Harbour Beach, Indialantic, Melbourne, Melbourne Beach, Palm Bay |
The Treasure Coast
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| AMZ555 | Sebastian Inlet to Jupiter Inlet 0-20 nm | Melbourne | Sebastian, Vero Beach, Fort Pierce, Port St. Lucie, Jensen Beach, Stuart, Port Salerno, Hobe Sound |
The Gold Coast
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| AMZ650 | Coastal waters from Jupiter Inlet to Deerfield Beach FL out 20 NM | Miami | Jupiter, Juno Beach, North Palm Beach, Riviera Beach, West Palm Beach, Palm Beach, Lake Worth Beach, Boynton Beach, Delray Beach, Boca Raton |
| AMZ651 | Coastal waters from Deerfield Beach to Ocean Reef FL out 20 NM | Miami | Deerfield Beach, Pompano Beach, Lauderdale-by-the-Sea, Fort Lauderdale, Dania Beach, Hollywood, Hallandale Beach, Sunny Isles Beach, Miami Beach |
| AMZ630 | Biscayne Bay | Miami | Miami, Key Biscayne, Cutler Bay |
The Florida Keys
| Zone | Name | Office | Towns on this coast |
|---|---|---|---|
| GMZ042 | Hawk Channel from Ocean Reef to Craig Key out to the reef | Key West | Key Largo, Tavernier, Islamorada |
| GMZ043 | Hawk Channel from Craig Key to west end of Seven Mile Bridge out to the reef | Key West | Marathon |
| GMZ044 | Hawk Channel from west end of Seven Mile Bridge to Halfmoon Shoal out to the reef | Key West | Big Pine Key, Key West |
| GMZ031 | Florida Bay including Barnes Sound, Blackwater Sound, and Buttonwood Sound | Key West | Key Largo, Tavernier, Islamorada |
| GMZ032 | Bayside and Gulfside from Craig Key to West End of Seven Mile Bridge | Key West | Marathon |
| GMZ035 | Gulf of America from West End of Seven Mile Bridge to Halfmoon Shoal out to 5 Fathoms | Key West | Big Pine Key, Key West |
| GMZ052 | Straits of Florida from Ocean Reef to Craig Key out 20 NM | Key West | Key Largo, Tavernier, Islamorada |
| GMZ053 | Straits of Florida from Craig Key to west end of Seven Mile Bridge out 20 NM | Key West | Marathon |
| GMZ054 | Straits of Florida from west end of Seven Mile Bridge to south of Halfmoon Shoal out 20 NM | Key West | Big Pine Key, Key West |
Neighbours on different water
A few miles can put two towns in different forecasts. Pensacola Beach reads the Gulf; Gulf Breeze, across Santa Rosa Sound, reads Pensacola Bay. Okaloosa Island reads the Gulf; Fort Walton Beach, across the sound, reads the bay zone, and Destin, at East Pass, reads Choctawhatchee Bay. Panama City Beach reads the Gulf and Panama City St. Andrews Bay. St. Pete Beach reads the Gulf; Gulfport and St. Petersburg, behind it, read Tampa Bay. Anna Maria and Holmes Beach read the Gulf, and Bradenton and Palmetto, across the bay’s mouth, Tampa Bay. Boca Grande, Captiva and Sanibel read the Gulf; Placida, Bokeelia and Matlacha, on the water behind them, read Charlotte Harbor and Pine Island Sound. Fort Myers, nine miles up the Caloosahatchee, has no zone on its river and reads the Gulf off Fort Myers Beach. Bonita Springs sits on the line between the Tampa Bay and Miami offices and reads Tampa Bay’s zone. If you are going out through a pass, read both: the one you leave from and the one you are heading into.
A bay forecast and a Gulf forecast read differently
The Gulf zones give the wind and the seas in feet, and often a Wave Detail line after them: each wave train by direction, height and period in seconds. A short period means close-set waves, steeper for their height.
The bay and sound zones give the wind and the waves in feet, often with the state of the water in words. From Tampa Bay south, a Gulf zone’s forecast also carries a line for the bay and inland waters beside it, in words: “light chop”, “a moderate chop”. On a bay the wind line is the one to read first. When two zones are expected to see the same weather, the office writes one paragraph headed with both names, and when they differ, each gets its own. Miami writes its Gulf zones as one paragraph, so Collier County’s forecast is shared with the waters south of Chokoloskee and beyond 20 miles.
What the words mean, in knots
These are the National Weather Service’s thresholds. The advisory threshold depends on the region; the warning thresholds do not change.
- Small Craft Should Exercise Caution. A headline, not an advisory. In the weather service’s Southern Region it is used for winds of 15 to 20 knots or seas of about 6 feet.
- Small Craft Advisory. In the Southern Region, which includes this coast: sustained winds of 20 to 33 knots, or forecast seas of 7 feet or more expected for more than two hours. The service says the thresholds are “specific to geographic areas”, and “There is no precise definition of a small craft”: whether your boat and your experience are up to it is your call.
- Gale Warning. Sustained winds or frequent gusts of 34 to 47 knots, not directly tied to a tropical cyclone.
- Storm Warning. 48 to 63 knots, likewise.
- Special Marine Warning. A short warning, usually for up to two hours, for thunderstorm winds or gusts of 34 knots or more, hail of three-quarters of an inch or more, or waterspouts.
- Tropical Storm and Hurricane Warnings. Gale and storm warnings are for wind not tied to a tropical cyclone; for a tropical storm or hurricane these are the warnings. A tropical storm warning means sustained winds of 39 to 73 mph are expected within 36 hours. A hurricane warning is issued 36 hours before tropical-storm-force winds are expected, because preparing becomes difficult once they arrive.
The line most often misread
A forecast of seas is a significant wave height: the average height of the highest third of the waves. So “seas 4 to 6 feet” is not the size of every wave; most are smaller, and some are bigger.
The weather service’s caution: wave forecasts are an average, and some individual waves “can be expected to be as much as two times greater.”
Read a forecast of six-foot seas as one that can include twelve-foot waves.
Sources
- National Weather Service Mobile, marine zone map, National Weather Service Tallahassee, marine and National Weather Service Miami, marine — the zones
- Mobile, Tallahassee, Tampa Bay and Miami coastal waters forecasts
- National Weather Service, marine warning and advisory definitions — the Southern Region thresholds and the warnings
- National Weather Service Southern Region, marine forecast supplement — Small Craft Should Exercise Caution
- National Weather Service, marine forecast FAQ — significant wave height and individual waves