Geography of Finland - Climate

Climate

Latitude is the principal influence on Finland's climate. Because of Finland's northern location, winter is the longest season. Only in the south coast summer is as long as winter. On the average, winter lasts from early December to mid March in the archipelago and the southwestern coast and from early October to early May in Lapland. This means that southern portions of the country are snow-covered about three to four months of the year and the northern, about seven months. The long winter causes about half of the annual 500 to 600 millimetres (19.7 to 23.6 in) of precipitation in the north to fall as snow. Precipitation in the south amounts to about 600 to 700 millimetres (23.6 to 27.6 in) annually. Like that of the north, it occurs all through the year, though not so much of it is snow.

The Atlantic Ocean to the west and the Eurasian continent to the east interact to modify the climate of the country. The warm waters of the Gulf Stream and the North Atlantic Drift Current, which warm Norway and Sweden, also warm Finland. Westerly winds bring the warm air currents into the Baltic areas and to the country's shores, moderating winter temperatures, especially in the south. These winds, because of clouds associated with weather systems accompanying the westerlies, also decrease the amount of sunshine received during the summer. By contrast, the continental high pressure system situated over the Eurasian continent counteracts the maritime influences, occasionally causing severe winters and high temperatures in the summer.

The highest ever recorded temperature is 37.2 °C (99.0 °F) (Liperi, 29 July 2010). The lowest, −51.5 °C (−60.7 °F) (Kittilä, 28 January 1999). The annual middle temperature is relatively high in the southwestern part of the country (5.0 °C/41.0 °F to 7.5 °C/45.5 °F), with quite mild winters and warm summers, and low in the northeastern part of Lapland (0 °C/32 °F to −4 °C/25 °F).

Temperature extremes for every month:

Extreme highs:

• January: +10.9 °C (51.62 °F) (January 6, 1973, Mariehamn, Åland)
• February: +11.8 °C (53.24 °F) (February 28, 1943, Ilmala, Helsinki, Southern Finland)
• March: +17.5 °C (63.50 °F) (March 27, 2007, Helsinki-Vantaa Airport, Vantaa, Southern Finland)
• April: +25.5 °C (77.90 °F) (April 27, 1921, Jyväskylä, Central Finland)
• May: +31.0 °C (87.80 °F) (May 30/31, 1995, Lapinjärvi, Southern Finland)
• June: +33.8 °C (92.84 °F) (June 24, 1934, Ähtäri, Central Finland)
• July: +37.2 °C (98.96 °F) (July 29, 2010, Joensuu Airport, Liperi, Eastern Finland)
• August: +33.8 °C (92.84 °F) (August 7, 2010, Heinola, Southern Finland, and Puumala, Eastern Finland)
• September: +28.8 °C (83.84 °F) (September 6, 1968, Rauma, Western Finland)
• October: +19.4 °C (66.92 °F) (October 2, 1985, Malmi, Helsinki, Southern Finland)
• November: +14.1 °C (57.38 °F) (November 2, 1999, Mariehamn, Åland)
• December: +10.8 °C (51.44 °F) (December 6, 2006, Salo, Southern Finland)

Extreme lows:

• January: −51.5 °C (−60.7 °F) (January 28, 1999, Pokka, Kittilä, Lapland)
• February: −49 °C (−56.2 °F) (February 5, 1912, Sodankylä, Lapland)
• March: −44.3 °C (−47.7 °F) (March 1, 1971, Tuntsa, Salla, Lapland)
• April: −36 °C (−32.8 °F) (April 9, 1912, Kuusamo, Northern Ostrobothnia)
• May: −24.6 °C (−12.3 °F) (May 1, 1971, Enontekiö, Lapland)
• June: −7 °C (19.4 °F) (June 3, 1962, Laanila, Inari, Lapland)
• July: −5 °C (23.0 °F) (July 12, 1958, Kilpisjärvi, Enontekiö, Lapland)
• August: −10.8 °C (12.6 °F) (August 26, 1980, Naruska, Salla, Lapland)
• September: −18.7 °C (−1.7 °F) (September 26, 1968, Sodankylä, Lapland)
• October: −31.8 °C (−25.2 °F) (October 25, 1968, Sodankylä, Lapland)
• November: −42 °C (−43.6 °F) (November 30, 1915, Sodankylä, Lapland)
• December: −47 °C (−52.6 °F) (December 21, 1919, Pielisjärvi, Eastern Finland)