Simplified ice chart and reference charts

About the charts

The ice chart of the whole Baltic Sea (pdf) is published in the autumn twice a week (Monday and Thursday) and daily when the amount of ice increases until ice break-up in spring. It represents current ice situation, ice breaker positions and assistance restrictions in the Baltic Sea.

The simplified charts are updated once a week at the latest on Tuesday morning. The first one represents measured level ice thicknesses, ice coverage and sea surface temperature. The reference charts represent average, 1965 – 1986, ice situation on that day (= normaali), last week´s situation, last year´s situation and the positions of the ice breakers.

 Products are generated using E.U. Copernicus Marine Service Information.

Explanation of chart's Finnish words

  • jäätä: ice

  • vettä: water

  • haurasta: rotten ice

Ice extent

Daily ice extent on the Baltic Sea (km²) based on the ice charts. The blue envelope curves show the largest and smallest ice extents (min–max) and fractiles (25 %–75 %) of the ice seasons 2007–2021. The green line (50 %) is the median extent of the seasons 2007–2021. The black dotted line is the previous ice season's (2021–2022) ice extent, and the solid black line is the current ice season's (2022–2023) extent.

The values are rounded so that areas less than 100 km² are with a precision of 10 km², from hundred to thousand square kilometres with 100 km² precision and larger areas with a precision of 1,000 km².

More information