Climate

The climate of Norway is surprisingly temperate for such a northerly country; this is mainly due to the North Atlantic Current with its extension the Norwegian Current warming the air temperature, and the prevailing southwesterlies bringing the mild air on shore.

Temperature

The coast experiences much milder winters than other areas at the same latitudes. The islands in southern Lofoten, to the north of the Arctic Circle in North Norway, are the most northerly locations in the world where all winter months have mean temperatures above 0°C. Finnmarksvidda has the coldest winters in Norway, but inland areas further south can also see severe cold; Røros has recorded -50°C. Spring is the season when the temperature differences between the southern and northern part of the country is largest; this is also the time of year when daytime and night-time temperatures differs the most. Inland vallys and the innermost fjord areas have less wind and sees the warmest summer days; the Oslofjord lowland is warmest with July 24-hr average of 17°C, but even Alta at 70°N has July average of 13.5°C, and commercial fruit orchards are common in the innermost areas of the western fjords. Inland areas reach their warmth peak around mid-July, and coastal areas by the first half of August. Humidity is usually low in summer.

The North Atlantic Current splits in two in the northern part of the Norwegian Sea; one branch goes east into the Barents Sea, while the other goes north along the west coast of Spitsbergen; this modifies the Arctic polar climate somewhat and results in open water throughout the year at higher latitudes than any other place in the Arctic. On the eastern coast of the Svalbard archipelago, the sea used to be frozen during most of the year, but the last years warming (graph) have seen open waters noticeably longer.

Normal monthly averages range from -17.1°C in January in Karasjok to 17.3°C in July in Oslo - Studenterlunden. The warmest year average temperature is 7.7°C in Skudeneshavn in Karmøy, and the coldest is -3.1°C in Sihcajarvi in Kautokeino (excluding higher mountains and Svalbard); this is a 10.8°C difference, about the same as the temperature difference between Skudeneshavn and Athens, Greece.

The warmest temperature ever recorded in Norway is 35.6°C in Nesbyen. The coldest temperature ever recorded is -51.4°C in Karasjok. The warmest month on record was July 1901 in Oslo, with a mean (24hr) of 22.7°C, and the coldest month was February 1966 in Karasjok with a mean of -27.1°C. Southwesterly winds further warmed by foehn can give warm temperatures in narrow fjords in winter; Tafjord has recorded 17.9°C in January and Sunndal 18.9°C in February.

Average daily minimum temperature in January is -6.8°C in Oslo, -4.8°C in Kristiansand, -0.4°C in Bergen and -6.5°C in Trondheim and Tromsø. The average daily high in July is 21.5°C in Oslo, 20.1°C in Kristiansand, 17.6°C in Bergen, 18.4°C in Trondheim and 15.3°C in Tromsø.

Precipitation

Some areas of Vestlandet and southern Nordland are Europe's wettest due to orographic lift, particularly where the moist westerlies first are intercepted by high mountains; this occurs slightly inland from the outer skerry guard. Brekke in Sogn og Fjordane has the highest annual precipitation with 3,575 mm; annual precipitation can exceed 5,000 mm in mountain areas near the coast. Lurøy, near the Arctic Circle, gets 2,935 mm on average, an amazing humidity for such a northerly area.

Precipitation is heaviest in autumn and early winter along the coast, while April to June is the driest. The innermost parts of the long fjords are somewhat drier, annual precipitation in Lærdal is 491 mm, in Levanger 750 mm and only 300 mm in Skibotn at the head of Lyngenfjord, the latter also has the national record for clear-weather days.

The regions to the east of the mountains (including Oslo) have a more continental climate with less precipitation, and enjoys more sunshine and usually warmer summers; precipitation is highest in summer and early autumn (often heavy showers not lasting long) while winter and spring tend to be driest inland. Valleys surrounded by mountains can be very dry compared to nearby areas, and a larger area in the interior of Finnmark gets less than 400 mm precipitation annually. Svalbard Airport has the lowest average annual precipitation with 190 mm, while Skjåk has the lowest average on the mainland with only 278 mm, the lowest ever recorded on the mainland is 64 mm at Hjerkinn in Dovre.

Monthly averages varies from 5 mm in April in Skjåk to 454 mm in September in Brekke. Coastal areas from Lindesnes north to Vardø have more than 200 days/year with precipitation; however this is with a very low threshold value (0.1 mm precipitation). Average number of days/year with at least 3 mm precipitation is 77 in Blindern/Oslo, 96 in Kjevik/Kristiansand, 158 in Florida/Bergen, 93 in Værnes/Trondheim and 109 in Tromsø.