Highest significant wave height
The highest significant wave heights are available from the Helsinki Map Service. By clicking "Detach" on the corner of the map, you can access the map service, where you can also download the data via a WFS interface.
The readings are given in metres. Red readings are based on wave buoy measurements, violet readings have been calculated from these.
If the numbers are not visible on the map, try to zoom closer.
Background information is available in the report Turvalliset rakentamiskorkeudet Helsingin rannoilla (in Finnish with English abstract) (pdf).