There is ice every winter

In the Baltic Sea, ice winters exhibit a lot of natural variation. Climate warming reduces the extent of ice cover and also shortens its duration. The Finnish Meteorological Institute, in co-operation with its Swedish counterpart, publishes a daily ice map of the Baltic Sea. It is based on satellite images and a variety of data sources, such as radar satellites, which produce images of the ice sheet in all weather and lighting conditions.

Each week, ice observers visit the pack ice to measure ice thicknesses. Such measurement readings also include the proportion of both clear and white ice. At the same time, the depth of the snow is also measured. The measurements only tell the situation at the observation point; nearby ice may be thinner or thicker.

The time-series data of ice thickness do not show any uniform change. The thickness of fast ice, i.e. sea ice that is "fastened" to the coastline or the seafloor in shallow areas, is likely to be more affected by variations in the amount of snow than by changes in air temperature.

See the latest ice map here: Ice conditions.

Current as well as former ice seasons´ observations of ice and snow on ice.

By clicking a station on the map, list or diagram of maximum thicknesses, you can see all the observations made there during the season.

On the map, setting the mouse on a station shows the last months observations.

The blue columns show the ice thickness and the snow depth on ice is shown as red.