Learn · Alaska Tides

About Alaska tide stations

Alaska has more coastline than the rest of the United States combined, but fewer than 30 permanent tide gauges. This page explains how NOAA covers 500+ Alaska locations with predictions despite so few physical sensors.

NWLON stations
27
Permanent Alaska gauges
Partner sites
~18
AWLW + ADNR
Prediction pts
500+
Harmonic + subordinate
Coastline
47
More than all lower 48
Station types in AlaskaTides
NWLON
27 stations
Permanent · Real-time
Gold-standard sites with live water level, wind, and temperature. Key locations: Anchorage, Juneau, Ketchikan, Seward, Sitka, Unalaska, Nome, Prudhoe Bay.
Harmonic
~250+ stations
Historical · Predicted only
Sites where NOAA operated a gauge for at least a full tidal epoch, then derived harmonic constituents. Predictions are generally reliable but no live data.
Subordinate
~200+ stations
Offset-based predictions
Tides estimated by applying time and height offsets from a nearby reference station. Accuracy degrades with distance and local complexity.
Partner
~18 sites
AWLW · ADNR
Alaska Water Level Watch and ADNR stations fill remote community gaps, especially in Western Alaska where permanent infrastructure is sparse.
Why so few permanent gauges?

Building and maintaining a tide gauge in Alaska is expensive — remote communities, harsh conditions, ice and storms threatening instruments and power. Even with 47,300 miles of coastline, Alaska has fewer than 30 permanent NOAA sensors.

This creates data gaps, especially along the Arctic and Western coasts. To fill them, agencies sometimes deploy GPS tide buoys or temporary sensors during ice-free months.

What this means in the app
NWLON stations
Best predictions + live water level data. Used for real-time chart and conditions on the home page.
Remote stations
May be based on shorter records or extrapolated from a distant reference — local conditions can differ more from the curve you see.
Always treat predictions as estimates
Use AlaskaTides alongside official charts, local experience, and real-time conditions. Marine safety disclaimer → Data accuracy →