In aeronautics, seasons are defined based on temperatures, known as thermal seasons. This precise definition helps to outline the changes in weather throughout the year. For example, winter is characterized by temperatures mostly below zero, while spring begins when the average temperature rises above zero. Similarly, summer is marked by temperatures mostly above 10 degrees, and autumn arrives when temperatures drop below 10 degrees again.
The duration of each season can vary depending on the location. For instance, on the southern coast of Finland, summer lasts approximately 130 days, while winter spans around 110 days. In cities like Helsinki and Turku, summer is slightly longer than winter, but as you move further north, the length of winter increases while summer shortens. In Tampere, the seasons are roughly equal in length, but in most of Finland, winter surpasses the duration of summer.
In the northern regions of Lapland, summer lasts less than three months, with winter extending for half a year. This results in winter being twice as long as summer in these areas. The differences in season lengths across Finland highlight the diverse climate conditions experienced in different parts of the country.