Tide Alerts Documentation

Find a station on a local waterway and read live or recent gauges. Open charts, tables, and calendars. Same app on iOS, Android, and the web. Browse the map, tables, and calendars without an account.
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What you can do

    Map, charts, and tables
    See live and recent water levels on the map. Then open charts, tide tables, and calendars for that station.
    Account and email alerts
    Sign in with Apple, Google, or email to keep favorites across devices. Subscribe to public email alerts.
    Weather and print
    Open a station weather tab for wind. No login. Print or share tide tables as PDF. Sync a live calendar into Apple Calendar, Google, or Outlook.

How Tide Alerts differs from other tide apps

Most tide apps reprint the same NOAA high and low tables. Those tables are historical averages. Many of those apps show no live water.

Tide Alerts uses live or recent readings at the station you pick. For NOAA stations it pairs those readings with NOAA predictions. It does not treat a neighboring bay’s NOAA station as if it were your creek.

Read why that matters.

What the numbers mean

A tide chart value is the height of the water surface above a zero such as MLLW. It is not how deep the water is. It is not how much room is under a bridge, unless that station has measured bottom and bridge datums.

Owners of Sentient Things tide stations have those measured datums today. The same treatment is coming to NOAA, SECOORA, NERACOOS, and USGS stations.

MLLW, NAVD88, and datums explains the ruler in plain language.

Coverage

Tide Alerts includes Sentient Things gauges and raw SECOORA, NERACOOS, and USGS stations. NOAA usually publishes no tide tables for those sites. Tide Alerts computes predictions from measurements at that station, so you get tables and calendars that often did not exist there. Those predictions stay tied to that location even if NOAA publishes a table nearby.

NOAA stations in the app provide live or recent readings with NOAA predictions. The map covers more than 450 tidal stations.

Limitations
  • Tide Alerts is not an official NOAA app. It does not claim to be more accurate than NOAA everywhere.
  • Email alerts ship today. Custom threshold alerts, push notifications, and SMS do not.
  • There are no in-app purchases. Hardware tide gauges (solar, cellular) are sold separately.
  • Data and forecasts are for awareness. They are not a substitute for official marine forecasts or your own judgment.