Two important factors influence Sweden's climate. These are its northern latitude (between 55 and 69° N) and the shelter from milder and wetter Atlantic winds by the mountains along its western border with Norway. Most of the country has a typical continental climate with a moderate to large temperature range between summer and winter. The exception to this is the south-west from Gothenburg to Malmo where winter temperatures are modified by an open ocean which rarely freezes. The enclosed waters of the Baltic Sea often freeze in winter, hence the east coast of Sweden is much colder. The high latitude means that much of the country has very long hours of daylight in summer and very short days in winter. North of the Arctic Circle (66° N) this amounts to 24 hours of sun and 24 hours of Arctic twilight in midsummer and midwinter respectively.
Precipitation is relatively low except on the higher mountains and is generally greater in summer than winter. North of Stockholm, much of the winter precipitation is snow. Winters become progressively longer and colder towards the north of the country and the average number of days with a mean temperature below freezing increases from 71 at Malmo to 120 at Stockholm and 184 at Haparanda near the Arctic Circle.
Temperatures are surprisingly similar in midsummer over much of the country. The long summer days help to raise temperatures in the north so that on fine days temperatures may be as high as in the south. A result of the changeable nature of Swedish summers is that visitors should not expect to find fine weather every day. A wet cool spell in summer in northern Sweden can be miserable.
Climatically, Sweden can be split into three regions.
Central & southern Sweden
This region is south of a line from the Oslo fjord to Uppsala on the east coast. It is the most densely populated and agriculturally productive area of Sweden, and is largely low lying with numerous lakes. Although the winters are quite cold and shorter than those in the north, the summers are relatively warm. Nowhere is precipitation heavy; summer and early autumn is the wettest period and much of the winter precipitation falls as snow. In some winters the snow cover may be prolonged and the harbours on the east coast have to be kept clear by icebreakers. Snow falls on an average of 60 days at Stockholm but it does not lie so long on the west coast. Summer temperatures are similar to those of southern England, but there are more hours of sunshine.
The north-east or the low-lying shores of the Gulf of Bothnia
Here winters are severe and become longer and colder northwards. The short summers are surprisingly warm for latitudes near or north of the Arctic Circle. Daily average maxima can be as high as 21 °C in July. Precipitation is quite low near the coast, but snow may lie for up to 120 days, a figure that increases inland with altitude.
The north-west and far north
This is mostly a plateau of moderate to high elevation. Temperatures are largely controlled by altitude and at higher levels snow cover persists all year. In sheltered valleys precipitation may be much less than the surrounding hills. Here during fine weather, winter temperatures fall very low while summer temperatures rise surprisingly high. The greater part of the area, however, has a severe winter climate with short, changeable summers.