Following the evolution of mean temperatures gives information on the progress of climate change. There are many factors that affect the temperatures. Annual and decadal temperature oscillations are related to changes in different weather types. Occasionally we get mild weather from southerly and westerly flows and occasionally colder weather from the north.
Finnish temperatures have risen approximately one degree Celsius since early 20th century. In Helsinki the urban heat island effect amplifies the warming trend. The temperature rise is not constant and it is partly obscured by the large natural variability which is characteristic for Finland. Globally however the temperature rise of over half a degree Celsius in the 20th century is statistically significant.