Sebastian Inlet Tides and Currents

The mean tide range is about 0.64 meters, a little over 2 feet, at the Sebastian Inlet bridge, but under 0.1 meters, roughly 3 to 4 inches, at the Sebastian waterfront on the Indian River Lagoon.

NOAA's bench mark sheet for station 8722004, Sebastian Inlet, places the old tide gage on the north fender of the State Highway A1A bridge and lists mean high water at 0.683 meters and mean low water at 0.041 meters above mean lower low water (NOAA). Those datums come from one year of readings, August 1969 to July 1970, adjusted to the 1983 to 2001 tidal epoch.

Station 8722029, Sebastian, Indian River, had its gage on the yacht club dock reached from Cleveland Street and Indian River Drive, with mean high water at 0.114 meters and mean low water at 0.021 meters (NOAA). Micco station 8721994 sat on the wooden fuel pier at Summit Landings Marina, 1.3 miles north of the U.S. Highway 1 bridge over Sebastian Creek, and logged only one month, April 1972, with a similar spread of 0.104 and 0.022 meters (NOAA).

The record highs make the same point. The highest water logged at the inlet gage was 1.174 meters on October 29, 1969, against 0.701 meters on October 19, 1973, at the Sebastian waterfront gage. All three Sebastian sets of datums rest on observations more than 50 years old, taken before the north jetty extension completed in 2003 (Sebastian Inlet District), so the published ranges are a historical baseline rather than a current survey.

High tide on the Sebastian waterfront comes about 2 hours and 20 minutes after high tide at Sebastian Inlet, based on NOAA's prediction offsets for the two stations.

NOAA predicts all three Sebastian stations as subordinate stations of 8723178, Miami Beach, Government Cut. The inlet station runs 48 minutes ahead of Government Cut at high tide and 24 minutes ahead at low tide, with heights at 0.93 and 1.0 of the reference (NOAA CO-OPS). The Sebastian, Indian River station lags by 92 minutes at high tide and 156 minutes at low tide, and its high tide height is set at 0.15 of the reference (NOAA CO-OPS). Micco lags 74 and 139 minutes with a high tide factor of 0.14 (NOAA CO-OPS).

A practical reading for the Sebastian riverfront: a predicted high at the inlet arrives at the Sebastian Yacht Club area well over two hours later and only a few inches high, and the Harbor Branch current study below found the tide accounting for only 33 to 49 percent of current variability inside the lagoon near the inlet. None of the three is a live gauge: NOAA lists each as a subordinate tide prediction station referenced to Government Cut, and its bench mark sheets describe where the gages were located.

Inside the lagoon, the main tidal current measured near Sebastian Inlet had an amplitude of 11.0 centimeters per second, falling to 7.6 centimeters per second 13 kilometers north; none of the sources checked gives a current speed between the jetties.

The Sebastian Inlet District calls the inlet a local knowledge, fair-weather inlet used largely by smaller recreational fishing boats, and the only charted inlet between Cape Canaveral and Fort Pierce, crossed by a fixed A1A bridge with 39 feet of vertical clearance (Sebastian Inlet District). The north jetty was extended to 1,000 feet in work completed in 2003, and the south jetty is 575 feet (Sebastian Inlet District).

West of the bridge the flow spreads out. A Harbor Branch study along the Intracoastal Waterway near Sebastian Inlet found the M2 tide dominant, with current amplitudes falling from 11.0 centimeters per second near the inlet to 7.6 centimeters per second 13 kilometers north, and the tidal share of the current record falling from 49 percent to 33 percent (FAU Harbor Branch). The M2 tidal wave moved at 5.5 kilometers per hour. Net along-channel flow ran south, toward the inlet, at 0.5 to 2.1 centimeters per second over the 42-day study, and low-frequency motion at all three sites was inversely related to wind stress.

Near Sebastian Inlet the central Indian River Lagoon flushes half its water in about 2 to 6 days, far faster than the northern lagoon, which can go over a year without ocean exchange.

The lagoon has five inlets along 156 miles, and it is almost 90 miles from Sebastian Inlet north to Ponce de Leon Inlet at New Smyrna Beach, so the southern lagoon is refreshed almost daily while parts of the northern end can wait over a year (WFIT, 2019). A 2003 study treated the central lagoon as tidally flushed because of its proximity to Sebastian Inlet, with dry season half-flushing times of 6 days in the northern central zone and 2 days in the southern central zone (Ocean and Polar Research).

A Harbor Branch model put the water entering and leaving the whole lagoon at 38.7 million cubic meters on an average semidiurnal cycle; the northern lagoon, with 65 percent of the surface area, supplies only 9 percent of that volume, while the southern part, with 18 percent of the area, supplies 63 percent (FAU Harbor Branch).

Live Sebastian Inlet readings come from Florida Tech and Sebastian Inlet District instruments on and off the north jetty, not from a NOAA tide gauge.

The District's network is a weather station on the north jetty and two acoustic Doppler current profilers about 0.5 kilometers north of the inlet in about 8 meters of water, measuring currents, waves, water temperature and water level (Sebastian Inlet District). The District lists State of the Inlet reports through 2025 and takes report requests at (321) 724-5175. Florida Tech's Coastal Processes Research Group posts real-time data from the north jetty station and an offshore profiler about 1,000 feet out (Florida Tech), and the jetty station is listed by NOAA's buoy center as SIPF1, owned and maintained by Florida Institute of Technology (NOAA NDBC). The District's navigation page also links a three-day inlet forecast of wave height, currents and water levels (Sebastian Inlet District).

On shore, beach warning flags stand at both the north and south jetty entrances, and their colors flag hazardous conditions and stinging jellyfish (Sebastian Inlet District).

Sebastian Inlet State Park says the Sebastian Inlet bridge replacement on Jimmy Buffett Memorial Highway was scheduled to start in May 2026, and beach access from the south side is unavailable during construction.

The park warns of traffic congestion, construction noise and possible changes to the campground entrance, and notes the north side can reach capacity on weekends (Florida State Parks). The park lists itself as open 24 hours a day, charges $8 per vehicle, and sits at 9700 South Highway A1A in Melbourne Beach, but a park notice effective November 12, 2025 moved the South Ranger Station to 8 a.m. to sunset, leaving round-the-clock entry at the North Ranger Station. The park manager has described its tidal cove as a popular destination for families, with a view of the inlet. The inlet itself was opened at its present location in June 1923 by the Sebastian Inlet District, formed May 23, 1919 (Sebastian Inlet District).

Last verified: October 14, 2026, on the NOAA, Sebastian Inlet District, Florida Tech and Florida State Parks websites.