Spring begins in Southern Finland in April, in Lapland even a month later. The growing season begins when the temperatures start to rise above +5 C. Generally, most of the snow is gone in April, in Lapland snow can be even found until May or June. The ice on the lakes breaks up at the end of April or early may in Southern Finland and in the North they last until the end of June. In the spring the night-time temperature is generally below zero. In spring, the mean daily temperature rises from 0°C to 10°C.

In summer, the mean daily temperature is generally above 10°C. Summer usually begins in late May in southern Finland and lasts until mid-September. Summer in Lapland starts about a month later and ends a month earlier than on the south coast. The regions north of the Arctic Circle are characterized by 'polar days', when the sun doesn't set at all. The Northern Finland have 73 such days every year. Even in southern Finland, the longest day (around Midsummer) is nearly 19 hours long. The warmest day of the year comes about one month after aphelion, around July 20, in the whole of Finland. The highest summer temperatures in the Finnish interior are from 32°C to 35°C.

In autumn, the daily temperature generally remains below 10°C. Autumn begins around the last week of August in northern Finland and about one month later in southwestern Finland. The growing season ends in autumn when the mean daily temperature drops below 5°C. This occurs around the last week in September in northern Finland and in late October or early November in southwestern Finland.

Winter sets during November in Southern and Central Finland. The permanent freezing of the lakes in Northern Finland starts generally in Mid-November. In Southern and Central Finland the lakes begin to freeze from the late November to early December. The first snowfalls occur from late September to early October. The permanent snow cover occur in Northern Finland in November. Southern Finland and coastal areas receive snow cover generally for Christmas. During the winter, the day is at its shortest. There is daylight for about six hours in Southern Finland. In Northern Finland the sun goes down, staying down from 26th of November. This period, called Kaamos, lasts until 16th of January.