May was record dry and exceptionally warm in places
Photo: Sofie Kåll / AdobeStock.In large parts of Finland, May started with rather warm temperatures, after which followed a clearly colder than usual period for a few days. The end of the month was very warm, which resulted in the month’s average temperature being unusually high in most places in Finland, even exceptionally warm in many parts of the western part of the country.
According to the statistics of the Finnish Meteorological Institute, the average temperature in May varied from approximately 14 degrees Celsius in the southern part of the country to about 5 degrees Celsius in Northern Lapland. The average monthly temperature in the western part of the country was 3-4 degrees higher than usual and 1-3 degrees higher than usual in the eastern and northern parts of the country. The last time that most parts of Finland experienced a warmer May than this was in 2018.
For example, in Kaisaniemi in Helsinki, the average temperature in May was 13.8 degrees Celsius. The month was about 1.8 degrees warmer than it would have been without the impact of climate change. The probability of such a warm May in the current climate is ten times higher than without climate change. The information is based on a peer-reviewed method by researchers at the Finnish Meteorological Institute.
There were 16 hot days in May, which is the new record for hot days in May. The previous record, 14 hot days, was from 2018.
The month’s highest temperature, 29.9 degrees, was recorded on 31 May at the Hattula Lepaa observation station. The lowest temperature of the month, -13.2 degrees, was measured on 8 May at the Tulppio observation station in Savukoski.
Exceptionally little rainfall in many places in May
In many places, May was exceptionally low in precipitation. Thus, new station-specific, low precipitation records for May were recorded nearly everywhere in the country. However, at the end of the month, in places heavy thunderstorms raised the precipitation levels of some individual stations close to the usual values of the month.
The highest precipitation in May (59.4 mm) was measured at the Savukoski village observation station. The greatest amount of precipitation in a single day, 43.4 millimetres, was measured in Mujejärvi, Nurmes on 30 May. The lowest precipitation during the month was recorded at the Mehtäkylä observation station in Kalajoki, where the precipitation was only 0.7 mm. According to preliminary data, Vihti in Hiiskula had the lowest rainfall in the station's measurement history with 2.8 mm. The station has been recording observations for 97 years.
Monthly accumulations of less than five millimetres were measured in May at approximately one in four observation stations that measure rainfall for the Finnish Meteorological Institute.
In Mid-May, there were still several dozens of centimetres of snow at observation stations in the northern part of the country, but by the end of May, the snow had melted away from all observation stations of the Finnish Meteorological Institute.
Plenty of sunshine in May with more lightning than usual
In May, the number of sunshine hours was considerably higher than usual, and in the southern and central parts of the country, it was even exceptionally high. For example, at the Ilmala observation station in Jokioinen, the sun shone for 384.6 hours in May, which is the highest reading in May in the 65-year measurement history of the observation station. However, May 2018 was even more sunny in places: at that time, more than 400 sunshine hours were measured at several observation stations in Southern Finland.
Ground discharges of lightning numbered about 22,400, which is over three times more than the average for 1991–2020 of about 6,600.
Spring was warmer than usual, but rainfall was typical of the time
The Finnish Meteorological Institute statistics showed that the average temperature for all of spring, i.e. March-May, varied between about six degrees Celsius in the south to about -3 degrees in the north-west arm of Finnish Lapland. The average temperature was about 1 degree higher than usual in the whole country. The last time the southern and central areas were as warm in May as they were this year was in 2016.
Despite the dry May, spring had quite usual rainfall in a large part of the country. Spring precipitation was the highest, 171.4 millimetres, at the Kotila observation station in Puolanka. The lowest rainfall was in Pudasjärvi airport, 55.4 mm.
More information:
Weather statistics from the Climate Service, tel. 0600 1 0601 (€ 4.01/min + local network fee)