Sea level and ice readings from the northern Baltic, as plain JSON.

One hundred and forty coastal gauges between Hanko and Kemi report every ten minutes. We clean the series, flag gaps and publish them for harbour offices, small ferries and researchers.

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140Active gauges
10 minUpdate interval
1971Archive starts
99.4%Series completeness

Sea level

Water height against the N2000 datum, with the harmonic tide removed so that storm surge shows up on its own line.

Ice

Ice thickness and concentration from fixed sensors and weekly survey flights, merged into one daily value per basin.

Harbour wind

Ten-minute mean wind and gusts at 28 piers, useful when a small ferry has to decide whether to leave.

Request example

GET /v2/stations/helsinki-kaivopuisto/level?from=2026-11-10&step=10m

{
  "station": "helsinki-kaivopuisto",
  "datum": "N2000",
  "unit": "cm",
  "readings": [
    { "t": "2026-11-10T00:00:00Z", "level": 14.2, "surge": 3.1 },
    { "t": "2026-11-10T00:10:00Z", "level": 14.9, "surge": 3.4 }
  ]
}