September once again record warm in many places

According to the statistics of the Finnish Meteorological Institute, the average temperature in September was record-high everywhere in Finland. The average temperature this year was 12.2 degrees. This shares the record with last year’s September. Comparable data extends to the early 20th century.

“It is unprecedented that the average temperature is record high during the same month in consecutive years in Finland,” said Meteorologist Pauli Jokinen from the Finnish Meteorological Institute.

September was record warm at observation stations in the eastern and northern parts of the country. For example, the average temperature in Tähtelä, Sodankylä was 10.3 degrees Celsius in September, which is the new record for September in the measuring history spanning over 110 years, breaking the old records from 1934 and 2023 by 0.3 degrees.

Climate change made the September in Sodankylä approximately 1.7 degrees warmer than what it would have been without the impact of climate change. The probability of a September this warm is approximately 23 times higher in the current climate than without climate change. The information is based on a peer-reviewed method by researchers at the Finnish Meteorological Institute and the University of Helsinki.

The average temperature in September varied between approximately 15 degrees Celsius on the southern coast to about 8 degrees in north-western Lapland. The deviation from the comparison period 1991–2020 was generally 2–4 degrees, with the largest deviation in eastern Finland.

The highest temperature in September (28.0 degrees) was recorded on the fifth day of the month in Yltöinen in Kaarina and Turku Airport. This is the highest September temperature since 1968, when the record temperature was 28.8 degrees. The lowest temperature of the month, -9.8 degrees Celsius, was recorded in Vuotso, Sodankylä, on 23 September.

There were as many as eight hot days in September, which is a new record for hot days in September. The previous record - five hot days - was from 1968.

More sunshine than usual

September was rainier than usual in a strip extending from Uusimaa to Koillismaa, and in some parts of Central Finland and Northern Savo, it was even exceptionally rainy. Rainfall in this area was twice as high as usual.

On the other hand, there was less precipitation on the coast of Ostrobothnia and in places in the eastern part of the country than usual. Especially North Karelia only experienced about half of the normal rainfall in September. Among other places, Tohmajärvi had the least precipitation in the 116-year history of the station this September.

According to preliminary data, the highest amount of precipitation was recorded in Lamminkäyrä, Lapinlahti (141.1 mm). The lowest precipitation levels were recorded in Pyhäselkä, Joensuu where the monthly precipitation was only 12.9 mm. The greatest precipitation in a single day, 57.4 mm, was recorded at the Jaurakkajärvi observation station in Pudasjärvi on 13 September.

The first snow was recorded in Kilpisjärvi, Enontekiö on the morning of 24 September with snow depth measured at three centimetres. First snow came a few days earlier than the median time of the comparison period 1991–2020. At the end of the month, there was only snow at the Inari Angeli Lintupuoliselkä observation station, where the snow depth was 11 centimetres.

In September, there were 130‒200 hours of sunshine. In both the south and the north, the sun shone 20‒40 hours more than usual.

A total of 3,641 cloud-to-ground lighting strikes were observed in September, below the average of 2,800.

Further information:

September weather statistics (in Finnish)

You can examine past weather statistics in the Download observations service

Weather statistics from the Climate Service, tel. +358 600 1 0601 (€ 4.01/min + local network fee)