Norway extends for about 1,100 miles between 58 and 71° N. The northern part of the country within the Arctic Circle has continuous daylight at midsummer and Arctic twilight all day in winter. Much of the interior is high mountain and plateau, whilst the largest area of lowland is in the south around Oslo, and this is the driest and warmest part of the country in summer.
The interior highlands have an Arctic type of climate in winter with snow, strong winds and severe frosts, but during fine summer spells the daytime temperatures can rise to the low 30s °C with long hours of sunshine. By contrast, the coastal areas have comparatively mild winter conditions under the influence of the Atlantic. This prevents the sea from freezing and keeps the harbours open.
Norway's weather and climate are very much influenced by Atlantic weather disturbances, resulting in changeable conditions throughout the year. Gales, rain and cloud are the dominant features of this coast, and the rainfall is frequent and heavy (in excess of 200 mm in each of the autumn months at Bergen). Rainfall decreases towards the north and snow is common at sea level in winter.
The Spitzbergen archipelago is situated in the Arctic Ocean between 77 and 80° N and has a severe Arctic climate. Winters are very cold and in the short summers, snow scarcely melts at sea level. The conditions at this time are very severe and also apply to northern and central parts of mainland Norway at higher levels.