Marine forecast — Sebastian, Florida

Sebastian Inlet is covered by the NWS Melbourne Coastal Waters Forecast, where the inlet splits zone AMZ552 to the north from zone AMZ555 to the south.

The marine forecast for Sebastian Inlet is part of the Coastal Waters Forecast for East Central Florida, a text product NWS Melbourne issues for the Atlantic coastal waters from Flagler Beach to Jupiter Inlet out 60 nautical miles. The forecast is broken into zones, and Sebastian Inlet is one of the dividing lines. Waters north of the inlet fall in zone AMZ552, Volusia-Brevard County Line to Sebastian Inlet 0-20 nm, and waters south of it in zone AMZ555, Sebastian Inlet to Jupiter Inlet 0-20 nm.

Farther out, the same split continues: AMZ572 covers the Volusia-Brevard County Line to Sebastian Inlet from 20 to 60 nautical miles, and AMZ575 covers Sebastian Inlet to Jupiter Inlet over the same distance. A synopsis section, AMZ500, opens the product with the weather pattern driving all six zones. A boat leaving Sebastian Inlet and turning north toward Melbourne Beach reads AMZ552, while one heading south toward Wabasso Beach and Vero Beach reads AMZ555, and an offshore run past 20 miles moves into AMZ572 or AMZ575.

Each zone also has its own web page. The AMZ555 page and the AMZ552 page on forecast.weather.gov carry the same text as the full product, period by period through the coming week, which makes them the quickest way to read the forecast for the waters on either side of Sebastian Inlet.

The synopsis is where the reasoning sits. The issue of 3:01 p.m. on October 10, 2026 explained that the remnants of Isaias were lifting into the Tennessee Valley while high pressure strengthened over the western Atlantic, that southerly flow would deliver poor boating conditions at times over the weekend with scattered showers and lightning storms, some of them offshore-moving and gusty, and that a front drifting into the waters from Sunday through Monday morning would turn winds northwesterly. Read with the AMZ552 and AMZ555 periods, that paragraph tells Sebastian Inlet boaters why the wind will change, not only when.

The Indian River Lagoon at Sebastian is covered by the chop rating for the intracoastal waters that closes each period of the AMZ552 and AMZ555 forecasts.

There is no separate lagoon zone in the Coastal Waters Forecast. Instead, every forecast period in the Atlantic zones ends with a description of conditions on the intracoastal waters, in steps such as mostly smooth, a light chop, a moderate chop and choppy. The Sebastian Inlet District notes that the inlet connects directly to the Intracoastal Waterway, which gives boaters access to the entire length of the 156-mile-long Indian River Lagoon, so that chop line is the forecast for the lagoon between Sebastian and the barrier island.

The AMZ555 forecast issued at 3:01 p.m. on October 10, 2026 shows how the wording shifts with the wind. For that night it called for south winds of 10 to 15 knots and a light chop on the intracoastal waters. For Sunday it called for a moderate chop, and for Sunday night, with winds around 5 knots, mostly smooth conditions. The forecast does not give a wave height for the lagoon; the chop rating is the only lagoon term in the product, so it is the line Sebastian boaters on the Indian River read first.

In the Sebastian Inlet forecast, seas give the range of the larger waves and wave detail lists each separate swell group by direction, height and period.

The Coastal Waters Forecast states its own definition at the top of every issue: seas are provided as a range of the average height of the highest one third of the waves, along with the occasional height of the average highest ten percent of the waves. A forecast of seas 2 to 3 feet off Sebastian Inlet therefore describes the typical larger waves, and individual waves higher than the range should be expected.

Below the seas line, the Wave Detail entry breaks the sea state into its separate wave groups, each with a direction, a height and a period in seconds. For the evening of October 10, 2026, the AMZ555 forecast listed southeast 3 feet at 4 seconds and northeast 2 feet at 8 seconds: a short wind chop from the south and east riding over a longer swell. Wave Detail gives one entry per group, so two lines in a Sebastian Inlet forecast mean two wave trains arriving from different directions at once.

The same product locates the Gulf Stream each day. Its Gulf Stream hazards section for October 10, 2026, based on the Real Time Ocean Forecast System, put the west wall 26 nautical miles east of Sebastian Inlet, compared with 33 nautical miles east of Port Canaveral and 15 nautical miles east of Fort Pierce Inlet. That figure tells offshore boaters how far east of the inlet the current lay on the day of issue.

A small craft advisory for the waters off Sebastian is a Weather Service alert that winds or seas in the AMZ552 or AMZ555 zone meet local hazard thresholds for small boats.

The National Weather Service glossary defines a Small Craft Advisory as an advisory issued by coastal forecast offices for areas included in the Coastal Waters Forecast, with thresholds that are specific to geographic areas. The glossary states that there is no precise definition of a small craft: any vessel that may be adversely affected by the advisory criteria should be considered one, along with the experience of the operator and the size and seaworthiness of the boat. For Sebastian boaters, the advisory appears as a headline at the top of the AMZ552 or AMZ555 zone text when it is in effect.

A lower level of caution also appears in the text. On October 10, 2026, the forecast for AMZ550, the zone off Volusia County, carried the headline SMALL CRAFT SHOULD EXERCISE CAUTION, while the two zones meeting at Sebastian Inlet carried none, a reminder that conditions can differ from one zone to the next on the same day.

Short-fuse products cover thunderstorms on the water. A Special Marine Warning issued at 5:30 p.m. on October 7, 2026 covered the Volusia-Brevard County Line to Sebastian Inlet from 0 to 60 nautical miles until 7:30 p.m. for severe thunderstorms capable of producing waterspouts. The next evening, a Marine Weather Statement issued at 7:52 p.m. on October 8 warned of a strong thunderstorm capable of producing winds to around 30 knots in the zones north of Sebastian Inlet. Both products are listed on the NWS Melbourne marine page, which also links tide predictions for Sebastian Inlet.

Conditions off Sebastian Inlet are reported by NOAA buoys 41114 to the south and 41113 to the north, buoy 41009 offshore, and station SIPF1 on the north jetty.

No wave buoy sits directly off Sebastian Inlet; the nearest two bracket it. To the south, station 41114, Fort Pierce, is a Scripps waverider at 27.564 N, 80.215 W in 16 meters of water. On the afternoon of October 10, 2026, it reported waves of 2.6 feet at a dominant period of 8 seconds from the northeast. To the north, station 41113, Cape Canaveral Nearshore, sits in 9.8 meters of water at 28.400 N, 80.533 W. Offshore, station 41009, a 3-meter discus buoy 20 nautical miles east of Cape Canaveral, adds wind, pressure and air temperature.

For the waters off Sebastian, the NWS Melbourne nearshore buoy page states that the U.S. Army Corps of Engineers deployed the Fort Pierce and Cape Canaveral wave buoys in September 2006, that they report wave height, period, direction and sea surface temperature hourly, and that the Weather Service broadcasts the information on NOAA Weather Radio. The buoys are maintained by the Coastal Data Information Program at Scripps Institution of Oceanography, and the page asks mariners never to tie up to them while fishing.

At the inlet itself, station SIPF1 on the Sebastian Inlet State Park north jetty reports wind and pressure from the Florida Institute of Technology. On October 10, 2026 at 2:45 p.m., it showed a wind speed of 15.0 knots. The same page notes that right whales are active off Florida from November to April, that speed restrictions of 10 knots apply to vessels 65 feet or greater in specific areas and times, and that approaching a right whale within 500 yards is illegal, rules that apply to the waters boats reach after clearing Sebastian Inlet.

Boaters off Sebastian hear the marine forecast on NOAA Weather Radio, which serves Indian River and Brevard counties from transmitters WWF69 and WXJ70.

Away from a phone signal, the marine forecast reaches Sebastian boaters by NOAA Weather Radio. The NWS Melbourne transmitter page lists WWF69 in Fort Pierce on 162.425 MHz and WXJ70 in Melbourne on 162.550 MHz among the transmitters serving Indian River County and Brevard County, the two counties that meet at Sebastian Inlet. The nearshore buoy page adds that the Weather Service broadcasts the readings from the Fort Pierce and Cape Canaveral wave buoys on NOAA Weather Radio, so the latest wave heights north and south of the inlet are part of the same broadcast cycle as the Coastal Waters Forecast.

The radio page also explains how alerts are tested: weekly tests of the alerting features run every Wednesday between 11 a.m. and noon, postponed to the next day when weather is active. For a boater at the Sebastian Inlet State Park marina or on the lagoon off Sebastian, a Wednesday tone at that hour is a routine test rather than a warning.