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

	Jokionen			Siikajoki			Sodankylä
period	6190	7100	8110	6190	7100	8110	6190	7100	8110
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
autumn	4,5	4,5	4,9	2,6	2,5	3,0	-0,6	-0,8	-0,3
winter	-6,6	-5,5	-5,3	-9,5	-8,6	-8,4	-13,9	-13,1	-12,6
year	3,9	4,3	4,6	2,0	2,3	2,6	-1,0	-0,8	-0,4

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

	Jokionen			Siikajoki			Sodankylä
period	6190	7100	8110	6190	7100	8110	6190	7100	8110
spring	91	97	103	88	86	93	84	92	100
summer	210	217	218	181	193	199	184	181	196
autumn	178	177	181	150	144	146	145	137	134
winter	102	115	125	92	100	103	87	99	97
year	581	606	627	511	523	541	500	509	527

Normal period

Weather conditions can vary significantly from year to year. Therefore weather of a certain year does not give an accurate depiction of climate. We need longer time periods, for example 30 years.

A 30-year normal period is:

Long enough so that one exceptional year does not control the averages too much.

Short enough so that climate does not change too much in that time.

The current climate statistics are based on the 1981-2010 observations. However the internationally recognised normal period is 1961-1990 as set by WMO.

Reports

Raportteja - Repporter - Reports:

2012:1 Pirinen, Pentti, Simola, Henriikka, Aalto, Juha, Kaukoranta, Juho-Pekka, Karlsson, Pirkko ja Ruuhela Reija, 2012.

Tilastoja Suomen ilmastosta 1981-2010 - Climatological statistics of Finland 1981-2010

ISSN 0782-6079

Report in Helda digital archives of the University of Helsinki

Mean and annual wind speed values have been amended on 10 April 2013.

Ilmastotilastoja Suomesta - Climatic statistics of Finland:

2002:1 Drebs, Achim, Nordlund, Anneli, Karlsson, Pirkko, Helminen, Jaakko ja Rissanen, Pauli, 2002.

Tilastoja Suomen ilmastosta 1971-2000 - Climatological statistics of Finland 1971-2000

ISSN 1458-4530

Liite Suomen meteorologiseen vuosikirjaan Nide 90 osa 1-1990 - Appendix to the Meteorological yearbook of Finland volume 90 part 1-1990:

Tilastoja Suomen ilmastosta 1961-1990 - Climatological statistics in Finland 1961-1990. Helsinki 1991.

Annual mean temperature and precipitation 1981-2010

Maps of the annual mean temperature and precipitation in the 1981-2010 normal period have been done by using the so called "kriging" analysis method. The maps give a good overview of the spatial variation of temperature and precipitation in Finland. However the resolution is not accurate enough for a more detailed look at individual locations.

Annual mean temperature (°C) on the left and annual average precipitation sum (mm) on the right during the 1981-2010 normal period.