The average temperature was high in September, especially in Lapland
Photo: Tuija Vuorinen.According to the statistics of the Finnish Meteorological Institute, across the country, the average temperature of September was the third warmest in measurement history. The average temperature was 11.9 degrees in September, which was some tenths of a degree lower than the record-high years of 2023 and 2024. Comparable data extends to the early 20th century.
Lapland’s September was record warm. In the Tähtelä measurement station in Sodankylä, the average temperature was 11.0 degrees in September, which means that September 2025 was the third consecutive record-warm September at the station. Climate change made the average temperature of September 2025 1.9 degrees higher and roughly 50 times more probable than if there were no climate change. The information is based on a peer-reviewed method by the Finnish Meteorological Institute and the University of Helsinki.
The average temperature in September varied between approximately 15 degrees Celsius in the southern coast and approximately 10 degrees in Northern Lapland. The deviation from the comparison period 1991–2020 was generally 2–4 degrees, with the largest deviation in Central Lapland. The average temperature was exceptionally high in many places from the southern part of the country to North Ostrobothnia.
The highest temperature in September, 25.8 degrees Celsius, was recorded on the 8th of the month at the Kärkkä observation station in Salo. The lowest temperature for the month, -5.4 degrees, was recorded on the 30th of the month at the Konnunsuo observation station in Lappeenranta.
There were four days when the temperature exceeded 25 degrees in September, which is an unusually large number.
September saw the highest number of lightning strikes since 2002
Precipitation levels were mostly normal or slightly higher than usual in September. The amount of precipitation was exceptionally high mainly in some areas of the southern parts of Central Finland and Northern Ostrobothnia. Some areas in the southern coast, near the eastern border and in the northern parts of Central Finland and North Savo had less precipitation than usually.
According to preliminary data, the highest amount of precipitation, 136.7 mm, was recorded in Sarakylä, Pudasjärvi. The least precipitation was received at the observation station of Pulju in Kittilä, where the monthly rainfall was 30.4 mm. The greatest amount of precipitation in a single day, 52.1 mm, was recorded at the Jyväskylä Airport observation station on 8 September.
In September, there were 80‒200 hours of sunshine, which is normal or a slightly higher number than usual.
A total of 6,700 cloud-to-ground lighting strikes were observed in Finland, when their average number for September is 2,800. The last September with a higher number of lightning strikes was in 2002.
Further information
Weather statistics from the Climate Service on weekdays, tel. +358 600 1 0601 (€ 4.06/min + local network fee)