About Tide Almanac

Tide Almanac shows predicted high and low tides for the tide prediction stations published by NOAA's Center for Operational Oceanographic Products and Services (CO-OPS), a month or a year at a time, in each station's own local time.

Where the numbers come from

Every prediction is NOAA's own, requested from the CO-OPS Tides & Currents service in UTC and metres, stored by this site's import jobs, and served from its own database. Pages never call NOAA while you wait, and every page says when its data was retrieved. Heights are relative to Mean Lower Low Water (MLLW) unless a page says otherwise; feet are converted from NOAA's metric values and rounded to a tenth, which can differ from NOAA's printed feet by 0.1 ft in about one tide per hundred.

Stations, not towns

Tides differ across a channel, an inlet or a bay, so pages are for specific NOAA stations and carry the station id in their address. Reference stations have their own harmonic predictions; subordinate stations are time and height offsets from a reference station, and NOAA publishes only their highs and lows, so no curve is drawn for them. The nearest station to you is not necessarily the right one for your shore; distances are shown so you can judge.

Time zones

Each station's local days are built in the IANA time zone of its coordinates, with daylight saving where that zone observes it; days with a clock change are 23 or 25 hours long and their tides fall where the local clock says. Where NOAA's own metadata lists a different standard offset, the page says so.

Not for navigation

Predictions are estimates of astronomical tides; actual water levels can differ due to weather and other conditions. This site is for planning a walk, a paddle or a fishing trip, not for determining safe clearance or when a vessel may depart. Consult official nautical charts, real-time observations, forecasts and local authorities for navigational decisions. See NOAA's disclaimer.

Sun and moon figures on day pages are computed from the station's coordinates and are not NOAA data. A sibling site, sunupsundown.site, covers sunrise and sunset in depth.