Mean temperature change

Updated: 3 Sep 2018
Next update: 3 Dec 2018

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.


Summer was exceptionally warm

In Finnish Meteorological Institute’s statistics summer (June-August) was approximately two degrees Celsius warmer than average. A summer this warm
occurs on average once every 20-30 years. In some locations summer was even more extreme than this though.

For example in Helsinki Kaisaniemi with a 174 year history, the summer of 2018 tied the record with the year 2011. In Sodankylä the summer was the
second warmest in 118 years of observations, only 1937 was warmer.

The highest temperature this summer was 33,7 °C in Vaasa on July 18th. This is the second highest annual maximum temperature in over 60 years, only the
record temperature from 2010 was higher (37,2 °C). The lowest temperature this summer was -5,0 °C and it was measured on June 7th at the fell station in

There were approximately 30 warm summer days (temperatures over 25 °C) in the southern parts of the country and about 20 in the north. This is 10-20 above
average. Out of individual stations, the most warm summer days was in Heinola, 36 in total. Temperatures over 25 °C were measured in some parts of the
country on 49 different days during June-August time period.