Normal period 1981-2010
The Finnish Meteorological Institute among many other meteorological institutes throughout Europe has published a climatological 30-year summary concerning the period of 1981-2010. The need of updated climatological 30-year statistics was obvious already in the end on 20th century. However, the former period 1961-1990 still remains the official normal period defined by WMO.
It is common nowadays that the long term climate statistics are updated every ten years. The new normal period 1981-2010 provides information on the current climatic conditions and is an important foundation when interpreting current weather phenomena.
Mean temperatures have risen
The annual mean temperature of Finland in the 1981-2010 normal period was almost 0,4 degrees higher compared to the previous normal period of 1971-2000 and approximately 0,7 degrees higher than in the official normal period of 1961-1990. The observed temperature rise is in reasonable agreement with the climate models.
The month of April has warmed up the most when comparing the new normal period to the previous one. June on the other hand is the only month when the monthly mean temperature in most of the country was cooler than in the previous period.
If we compared the new normal period to the official 1961-1990 values, we can see that the temperature rise has been most notable during winter months. In this comparison June is still the only month where slight cooling is observed.
It should be noted that changes in the observation stations themselves, measuring techniques and the WMO guidelines result in the fact that the different normal periods are not fully comparable with each other.
Seasonal and annual mean temperatures in Jokioinen, Siikajoki and Sodankylä for the three different normal periods
|spring|| 2,8||3,2||3,6|| 1,1||1,4|| 1,7||-1,9||-1,5||-1,2|
|summer||14,8||14,9||15,2|| 13,9||13,9||14,2|| 12,3||12,4||12,6|
Mean temperature in 10-year periods
The changes in the mean temperatures can also be viewed in 10 year periods. In the figure below, the 10 year mean temperatures are shown for Helsinki and Sodankylä spanning in total approximately 100 years each.
The 10 year mean temperatures in Helsinki are based on the annual mean temperatures since the year 1900. The temperature series in Sodankylä starts in the year 1910.
No big changes in precipitation
The annual variability in precipitation is large in Finland, at least when comparing to temperature. The average annual precipitation in Finland is slightly higher in the new normal period than in the previous normal period.
The monthly average precipitation in May is higher in the new normal period, whereas precipitation in April and September is less.
Seasonal and annual precipitation sums in Jokioinen, Siikajoki and Sodankylä for the three normal periods