The storm that hit the country on St Stephen's Day can be considered rare but not exceptional. The previous storm of this type in Finland was Janika in November 2001.
An extremely deep area of depression moved to Finland on St Stephen’s Day, travelling east over North Ostrobothnia and Kainuu. The winds reached their peak to the south of this depression between early night and afternoon. Storm force winds (average wind speeds over 10 minutes of 21 m/s at minimum) were measured in nearly all Finnish sea areas. According to observations made by the Finnish Meteorological Institute, the highest average wind speed of 28.5 m/s was measured off the town of Kaskinen. Similar average wind speeds are registered by the maritime observation stations a few times every decade.
Over land areas, wind damage was caused by momentary gusts. The most violent gust on land areas, or 31.5 m/s, was measured in Sepänkylä, Espoo. Several observation stations recorded gusts exceeding 20 m/s, especially in western parts of the country.
A high number of stormy days was recorded in December. By Tuesday 27 December, storm force winds in sea areas had been observed on 11 days. An equally high number of stormy days was last recorded in December 2003.
St Stephen’s Day was exceptionally mild, also in southern parts of the country. At many observation stations, this was the warmest Christmas in 50 years of records. The highest temperatures were measured at Mariehamn airport and on the island of Kemiö, or 9.9 degrees. The last very mild Christmas period in Finland was in 2006, in which year the maximum temperature went up to 8.9 degrees in Jomalaby in the Åland Islands on Christmas Eve.
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