Marine Safety Disclaimer

AlaskaTides.app is a digital tidebook for Alaska built on top of official NOAA Center for Operational Oceanographic Products and Services (CO-OPS) data and related public information. It is a planning aid only and is not approved for navigation or for safety‑critical decision‑making.

Data source

Tide predictions in this app come from the NOAA CO-OPS Tides & Currents API (api.tidesandcurrents.noaa.gov) for official Alaska tide stations. Predictions are generated by harmonic analysis, where NOAA sums 37 primary astronomical tide constituents for each station to estimate tide height through time.

For more background on how many tide stations exist in Alaska, how they are distributed, and how predictions are extended to hundreds of additional locations, see our About Alaska tide stations page.

Heights are shown relative to the local tidal datum Mean Lower Low Water (MLLW). To estimate actual water depth at a charted location, add the predicted tide height to the charted depth (for example: chart depth + water level = approximate depth).

Updates and accuracy

NOAA periodically re-analyzes gauge records and updates each station’s harmonic constituents and datums. When NOAA publishes new harmonics or station metadata, those changes flow through to this app automatically via the NOAA API.

Based on NOAA’s own published assessments, typical tide-prediction accuracy in well-observed locations is on the order of about 0.1–0.3 hours in timing and about 0.3–0.6 feet in height. Actual performance varies by station, season, and local conditions.

Limits and extreme conditions

Harmonic tide predictions account for astronomical tides only. They do not include short-term effects from wind, atmospheric pressure, river flow, ice, storm surge, or seiches. During storms, strong winds, low or high pressure systems, or unusual runoff, the observed water level can differ substantially from the predicted tide.

In remote areas with sparse observations, fewer years of gauge data, or complex bathymetry, prediction errors can be larger than the typical values above. Always treat predictions as an estimate, not a guarantee.

Safety and responsibility

Always consult official NOAA publications, local notices to mariners, and on-the-water conditions before making navigation or safety decisions. Use conservative margins around low-clearance transits, bar crossings, and beach access, especially in Cook Inlet and other high-range areas.

Conditions on the water can change rapidly. No app or website can replace experience, training, proper equipment, and the use of multiple independent, authoritative sources. You are solely responsible for maintaining safe margins and exercising sound judgment and seamanship at all times.

Legal notice and limitation of liability

AlaskaTides.app and all information, data, and services provided through it are offered “AS IS” and “AS AVAILABLE”, without any warranties of any kind, whether express, implied, or statutory, including but not limited to implied warranties of accuracy, fitness for a particular purpose, merchantability, or non‑infringement.

To the maximum extent permitted by applicable law, AlaskaTides.app and its owners, operators, contributors, and affiliates are not liable for any injury, death, property damage, or other losses arising from or related to your use of, or reliance on, this app or its information. Mariners remain solely responsible for the safe operation of their vessels.

More information

- NOAA Tides & Currents: tidesandcurrents.noaa.gov
- NOAA Information Quality Guidelines: Information quality