Ice Winter Severity Indicator—Swedish Coast

Because of large regional variability, an ice winter in the Bay of Bothnia may be classified as weak while ice conditions in the southern Baltic as severe. The ice season of 1962/1963 is the 

January and February. In the Bay of Bothnia, the mean temperatures were almost normal. 

The ice season of 1965/1966 was the opposite. January and February were very cold, especially in the north. Severe ice conditions prevailed in the Gulf of Bothnia and in the northern Baltic, while conditions were somewhat milder in the southern Baltic. This ice winter was very long, especially in the northern Baltic and Sea of Bothnia. The last ice disappeared from these areas as late as the beginning of May, while in the northern Bay of Bothniaremnants of ice lasted until early June. The southern Baltic was ice-free early, at the beginning of March. 

Another unusual case was the ice season of 2002/2003. Northerly and northwesterly winds and cold weather caused extremely severe ice conditions in the Gulfs of Finland and Riga in February and March, while ice conditions in Swedish waters were fairly normal. 

In mild ice winters, mild southwesterly or westerly winds prevail. Ice forming at sea in the Bay of Bothnia and at times in the Gulf of Finland breaks up and compresses off the Finnish coast, where locally severe ice conditions may occur temporarily. 

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