Tiedote - The warmest winter in Finnish measurement history
Photo: Eija Vallinheimo
In many parts of the country, this winter's new mean temperature record is almost one degree higher than the previous one. According to the statistics kept by the Finnish Meteorological Institute, the mildest winter so far had been the winter of 1924-1925.
The mean temperature for December-February was as much as 4 to 6.5 degrees higher than the average for the period 1971-2000. In Southern and Central Finland, the mean temperature for December-February was +1.5 to -4°C and in Northern Finland -3 to -8°C. Typically the mean temperature during winter is below the freezing point in all of Finland.
Between December and February, the number of winter days when the daily mean temperature was below zero totalled 20-30 in Southern Finland and 45-55 in Central Finland. Typically the number of such winter days varies between 60 and 80 in Southern and Central Finland. In Lapland, the number of cold winter days was about ten fewer than usual in December-February. Normally the daily mean temperature in Lapland remains below zero almost every day in winter.
Climate change has raised temperatures in winter
The main reason for the record mild winter is atmospheric currents that remained unusually steady all winter. For most of the winter, air currents came to Finland from the south and southwest. Among other things, the fact that the surface temperature of the Atlantic Ocean was higher than average affected the temperature of these air currents.
Global warming also contributed to the record-high temperature readings. It has been estimated that climate change raised the winter's temperatures by over one degree. Since 1990, more than two out of three winters have been warmer than average. The thermal conditions of the winter experienced in the Helsinki area can be compared with the winter climate in Denmark. Similarly, the winter in Central Finland can be compared with the average winter conditions in the inland areas of Southern Sweden.
Although the winter was relatively mild in Northern Europe and in Siberia, some very low temperatures have been measured in the Middle East, in Central and Eastern Asia, and in the western regions of North America. It is assumed that the factor behind the cold weather in the Pacific region is La Niña.
Winter also exceptionally rainy in places
Precipitation measured in all of Finland between December and February was higher than average. The number of days with rain and sleet was clearly more than usual. In large areas of westernmost Finland and in Oulu Province, the sum of precipitation for the winter was over 1.5 times the long-term average. The three-month sum of precipitation ranged between 120 and 250 millimetres in Southern and Central Finland, Oulu province and Southern Lapland, and between 60 and 140 millimetres in Central and Northern Lapland. The highest figure, over 320 millimetres, was measured in Lövböle of Kemiö on the southwest coast.
Snow cover in Southern and Central Finland thinner than average
In Southern and Central Finland and in the western areas of Oulu Province, the snow cover has remained thinner than average all winter. At the end of February, the snow cover was thin or the ground was completely bare in southern and southwestern parts of the country. The number of days when there was at least once centimetre of snow on the ground totalled 20-30 in Southern and Southwestern Finland, and 50-60 in Central Finland. Snow typically covers the ground even in the south on more than 70 days between December and February. In Lapland, in eastern parts of Oulu Province and in northern parts of North Karelia, the snow cover was normal at the end of February; in places it was even thicker than usual.
There were fewer sunny days than average in winter, especially in Southern and Central Finland. Together with the sparse snow cover, the scarcity of sunshine made the winter seem particularly dark. In some areas of Southern and Central Finland, the number of hours with sunshine was less than half of the usual amount for December-February.
February 4 to 6 degrees warmer than usual
In February, the mean temperatures were +1 to -4°C in Southern and Central Finland, +1 to +2°C on the south and southwest coast, and -3 to -9°C in Northern Finland. Thus, February was 4-6 degrees warmer than usual in the whole country. Before this, higher mean temperatures for February were measured, for example, in 1989 and 1990. For instance in Turku, Helsinki and Oulu, the past February was the third warmest. This winter's lowest temperature so far,-33.7°C, was measured on 24 February in Pokka of Kittilä. Around the same time, unseasonably high temperatures were measured in Southern and Southwestern Finland. The highest reading for the winter, +9.2°C, was also recorded on 24 February - in Jomala, on the Åland Islands.
Precipitation figures for February were higher than the average in almost all of Finland: 30-70 millimetres in Southern and Central Finland, and 15-40 millimetres in Northern Finland. The highest reading, 90 millimetres, was recorded in Nummi-Pusula in Uusimaa.