Data4 min

Why some spots show tide times and others don't

How far the nearest NOAA tide station really is from the water people swim in, measured across every spot on this site, and what that means for the number on the page.

Most spots on this site show tide times. A few say tide predictions are not available. The difference is distance, and it is worth knowing how far away the tide you are being shown was actually measured.

NOAA runs 3,499 tide prediction stations around the United States and its territories. Tides here come from whichever one is nearest a spot, and if the nearest is more than 150 km away the site declines to show a tide at all rather than pass off a reading from another stretch of coast.

How close the nearest station usually is

Across the 86 spots in the index, the median distance to the nearest station is 1.6 km. 65 of 86 sit within 5 km of one. For most of the coast the tide you see was measured close enough to be the tide you are standing in.

RegionSpotsMedian km to a station
Florida Keys90.5
Florida Panhandle40.7
Florida Gulf Coast81.4
Southeast Florida161.5
Northeast & Mid-Atlantic71.6
Carolinas & Georgia51.8
Pacific Northwest & Alaska41.9
California112.3
Space Coast & Northeast Florida63.2
Gulf Coast43.7
Hawaiʻi127.1
Median distance from each spot to its nearest NOAA tide prediction station, by region. Computed at build time from the bundled station list, so these numbers are the ones the site is actually using.

The spread is the interesting part. The Florida Keys are the best-covered water here, with a median under a kilometre. Hawaiʻi is the thinnest, at several times that. An island chain has a great deal of coastline per station, and a station on the far side of an island is a weaker guide to your beach than one along the same shore.

Where it runs out

Spotkm to nearest stationNearest station
Flower Garden Banks160.0Fieldwood WC-289 Platform
Anacapa Island20.5Port Hueneme
Cannon Beach18.8North Fork, Nehalem River
Surfrider Beach16.6Santa Monica, Municipal Pier
Honolua Bay15.3Lahaina
The five spots furthest from a tide station.

Only Flower Garden Banks sits past the 150 km cutoff, which is why that page shows no tide. It is roughly a hundred miles into the Gulf of Mexico, so there is genuinely no nearshore station to borrow from. The gap after it is steep: the next furthest spot is inside 21 km.

What this means for the number on the page

A tide time is a prediction for a specific station, not for your beach. Where the station is a kilometre up the same shoreline the difference is small enough to ignore. Where it is ten kilometres away around a headland, the timing can shift and the range can differ. Treat the reading as approximate.

Every spot page names the station its tide came from, so you can see how far you are trusting it. That is also why the site keeps its own copy of the station list: when NOAA's station directory went down for an afternoon, tides vanished from every page, and the whole index quietly stopped answering the one question it exists to answer.