Climate

Latitude is the principal influence on Finland's climate. Because of Finland's northern location, winter is the longest season. On the average, winter lasts 105 to 120 days in the archipelago and 180 to 220 days 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 50-60 cm of precipitation in the north to fall as snow. Precipitation in the south amounts to about 60-70 cm annually. Like that of the north, it occurs all through the year, though not so much of it is snow.

A quarter of Finland's territory lies above the Arctic Circle, and as a consequence the midnight sun can be experienced - for more and more days, the further up north one comes. At Finland's northernmost point, the sun does not set for 73 consecutive days during summer, and does not rise at all for 51 days in winter.

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, causing severe winters and occasionally high temperatures in the summer.

Helsinki

In Helsinki (elevation 45 m), average temperatures are at their lowest in February at -6°C (with a minimum of -9°C and a maximum of -4°C), and their highest in July, at 17°C (with a minimum of 13°C and a maximum of 21°C). Rainfall averages from 4 to 7 cm a month, with the greatest amounts falling from July to December (6 cm a month or more), with the least (less than 5 cm) falling from February to May.

Sodankyla

In Sodankyla (elevation 178 m) in the north of the country, average temperatures are at their lowest in January at -14°C (with a minimum of -19°C and a maximum of -10°C), and their highest in July, at 15°C (with a minimum of 9°C and a maximum of 20°C). Rainfall averages from 2 to 7 cm a month, with the greatest amounts falling from June to September (5 cm a month or more), with the least (3 cm or less) falling from January to March.