Press release 5.10.2023

Record-breaking temperatures in September

September in Kaisaniemi, Helsinki was the warmest in the station’s measuring history spanning over 180 years. The first snow fell in Finnish Lapland.
Photo: Hannele Sartjärvi.

According to the Finnish Meteorological Institute’s statistics, September’s average temperature reached record-breaking levels in the area extending from the southern part of the country to Central Lapland. In Northern Lapland, the average temperature in September was exceptionally high in places. For example, the September average temperature in Kaisaniemi, Helsinki was 15.8 degrees Celsius, which is the new record for September in the measuring history spanning over 180 years, breaking the old record from 1934 by 0.9 degrees.

The average temperature in September varied between approximately 16 degrees Celsius on the southern coast to just under 8 degrees in the northwest of Finnish Lapland. The deviation from the average for the 1991–2020 reference period was largely 2–3 degrees Celsius warmer.

The average temperature for the whole of Finland in September was 12.2 degrees Celsius. This is the highest average temperature in September in the measuring history beginning from the start of the 20th century. The previous average temperature record for September is from 1934 when September was 0.4 degrees Celsius colder than September this year.

The highest temperature in September, 24.1 degrees Celsius, was recorded on the 12th of the month at the Kouvola Utti Lentoportintie observation station. The lowest temperature was -5.9 degrees recorded at the Savukoski Tulppio observation station on 15 September.

Exceptionally high precipitation levels in the north

September was exceptionally rainy in most parts of Finnish Lapland. In addition, the precipitation levels were rare in many places in the central part of the country, Northern Ostrobothnia and Kainuu, even exceptionally high in some places. On the other hand, the precipitation levels were usual or lower than usual in the southern part of the country.

According to preliminary data, the highest precipitation levels were recorded in Paljakka, Puolanka where it rained 179.4 mm in September. The lowest precipitation levels were recorded in Utö, Parainen where the monthly amount of precipitation was only 19.4 mm. The greatest amount of precipitation in a single day, 65.5 mm, was recorded at the Hattula observation station in Sulkava on 12 September.

The first snow recorded in statistics fell in the area extending from Enontekiö to Inari on the morning of 20 September. At that time, the snow depth recorded in Kenttärova, Kittilä was as high as 23 cm. First snow fell in Finland earlier than usual: it typically falls in Central and Northern Lapland at the turn of September and October. The snow melted in three days, and there was no snow at any of the Finnish Meteorological Institute’s observation stations at the end of the month.

In September, 80–170 hours of sunshine were recorded, which is close to the typical number in September.

A total of 1,254 cloud-to-ground discharges were observed in September, well below the average of 4,400 for the whole month.

Further information:

Meteorologists call a weather phenomenon exceptional when its statistical occurrence is three times or less in 100 years on average. A phenomenon is seen as rare when it occurs less frequently than once every ten years on average.

Weather statistics from the Climate Service, tel. 0600 1 0601 (€4.01/min + local network fee)