The mean annual temperature is about 5.5 C in southwestern Finland, decreasing towards the northeast. The 0 C mean limit runs slightly to the south of the Arctic Circle. Due to the warming influence of the Arctic Ocean, the coldest spot in Finland in terms of average annual temperature is not in the far north of Lapland, but in the northwest corner of Finland. At the same latitudes elsewhere, this temperature difference varies even more greatly, from a few degrees in the North Atlantic to over 60 C in central Siberia. Wind and storms Since Finland is located in the zone of westerly air disturbances, there are great variations in air pressure and winds, especially in winter.
Wind speeds are typically highest in winter and lowest in summer.
Humidity and fog Humidity is dependent primarily on temperature. The humidity of the air is highest in July and August and lowest in February. Like temperature, humidity decreases towards the north. The figure does not vary very much within any region in any season. Fog is most common in autumn, in southern and southwestern Finland, usually at night and early in the morning.