Northern Norway - Climate

Climate

There are large climatic differences from southwest to northeast in this region. Finnmarksvidda in the interior of Finnmark and some valleys in the interior of Troms, experience a more continental climate with much less precipitation and much colder winters compared to the long coastal region.

Maritime to continental subarctic climate Brønnøysund in the southern part of Nordland has January and February averages of -1°C and -0.6°C (31°F), July & August 24-hr averages are both 13°C (56°F), year average is 5.6°C (42°F; about the same as in Oslo), and precipitation is 1,510 mm/year, with autumn as the wettest season . Brønnøysund experiences on average 63 days/year with strong breeze (22 knots) or more, and 18 of these days reach gale force winds or more (34 knots, data from Leka just south of Brønnøysund, source met.no). In all areas, late autumn and winter is the most windy time of year, as the Atlantic low pressure systems are strongest then.

Karasjok in the eastern part of Finnmarksvidda has January and February averages of -17°C (1°F) and -15°C (4°F), July & August averages are 13°C (56°F) and 11°C (52°F), year average is -2.4°C (28°F) and precipitation is only 366 mm/year . Situated in a river valley, Karasjok only experiences on average 1 day/year with strong breeze (22 knots) or more, and virtually never sees gale force winds.

The mean annual temperature difference between Brønnøysund and Karasjok is 8°C (15°F), about the same as the difference between Brønnøysund and Madrid, Spain . The comparatively mild maritime climate dominates along the coast and in the large fjords, even at the most northern coastal locations; in Nordkapp municipality the average January temperature is a modest -4°C (26°F) and the year average is 2°C (35°F) . Some islands, like Træna and Røst, have average temperatures of approximately 1°C (33°F) in their coldest months.
The warm climate in coastal areas, relative to other locations at the same latitude, is by many attributed to the relatively warm North Atlantic Current, an extension of the Gulf Stream. It has been shown that northern Europe's mild climate is caused primarily by intercontinental weather patterns driven by North America's mountain ranges. But in Northern Norway, this ocean current fundamendally changes climate.

Wind

The most windy location in continental Norway (apart from mountain summits) is Fruholmen lighthouse in Måsøy not far from the North Cape. The most windy city in Northern Norway is Bodø with on average 153 days/year with strong breeze or more and 24 days with gale force winds, while Vardø, also lacking shelter, sees 136 days of strong breeze or more and 18 days with gale. Inland valleys and sheltered fjord areas — particularly if sheltered by mountains — are much less windy. Tromsø, partly sheltered by large islands, experiences on average 27 days/year with strong breeze, and 1 day with gale, and Bardufoss sees on average only 11 days with strong breeze or more and scarcely ever experiences gale. In winter, there might sometimes blow cold winds from the freezing highlands out through the large fjords, -10°C and strong breeze will feel very cold on the skin. Mild westerlies are still much more common in most winters. Weather patterns are inherently unpredictable in this northern region — both low pressure and high pressure weather can occur at any time of year, although the strongest winds occur in winter.

Winter

Along the coast of Nordland average temperatures hover barely below freezing for 2 – 3 months, statistically from 15 December to 27 February in Brønnøysund; somewhat longer into the fjords. Inland Finnmark, as in Karasjok, average temperatures remain below freezing for 7 months (October — April). In Tromsø, average temperatures stays below freezing for 5 months - statistically from 10 November to 10 April (based on 1961-90 average, more recent years have tended to be somewhat warmer).

Summer

Even if winter temperatures depends largely on the distance to the sea, the length of the season varies mostly with latitude (and altitude): The summer (days/year with 24-hr average 10°C or more; 50°F) lasts on average 108 days in Brønnøysund, 90 in Bodø, 85 days in eastern Lofoten and Narvik, 75 days at the inland valleys of Bardufoss and Alta, about 65 days in Tromsø and Kirkenes, 50 in Hammerfest and 0 in Vardø. This is based on a 30 year average (1961–1990) for each day of the year; even Vardø will on occasions experience summer days. Statistically, summer temperatures starts 29 May in Brønnøysund and 22 June in Tromsø. The growing season varies from 180 days at Vega, Brønnøysund and Røst to less than 120 days in Finnmarksvidda and the Varanger Peninsula.

Precipitation

Precipitation occur in all seasons, usually as snow in winter, although often as rain on the Nordland coast. Snow accumulation in the mountains can exceed 3 m, and this abundance of snow is the reason for the numerous glaciers - more than 500, mostly in Nordland and Troms. Autumn tend to be the wettest season in most areas, often receiving more than twice as much precipitation as does spring and early summer. Only the interior areas of Finnmark - like Karasjok - tend to be wettest in summer. The areas with the least precipitation are some inland valleys, like Dividalen in Målselv with only 282 mm precip/year, and upper Saltdal and Skibotn with about the same. Inland Finnmark is the only large area with less than 450 mm precipitation/year. The wettest areas are generally the Helgeland region; Lurøy on the west coast of Saltfjell averages 2900 mm/year.

The Arctic northeastern coast

The extreme northeastern coast, from Nordkapp to Vardø, is situated in the arctic climate zone due to lack of summer warmth — July average in Vardø is only 9°C (48°F). However, 150 km to the south, in the Pasvik valley south of Kirkenes, July 24-hr average is up to 14°C (57°F). No other parts of Norway experience such large differences in lowland summer temperatures in such a relatively short distance.

Record temperatures

The coldest temperature recorded is -51.4°C (-61°F) in Karasjok, and the warmest recorded is 34.3°C (94°F) in Sihcajavri in Kautokeino.