Press release 7.10.2020

September was warmer than usual

Especially in the western part of the country, September was unusually warm. The precipitation levels varied from exceptionally high to lower than normal, with the highest rainfall received in the central parts of the country. On Aila's name day, an exceptionally powerful storm passed over Finland.
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According to the figures of the Finnish Meteorological Institute, the mean temperature for September was higher than normal throughout the country. The average temperature varied from approximately 14°C on the southern and southwestern coast to just over 6°C in the north-west of Finnish Lapland. Generally, the deviation from the long-term average was 1–2 degrees. The biggest deviation was in the western part of the country, where September was unusually warm. Similar conditions happen less than once every 10 years. This was already the 12th consecutive September that was warmer than average. Last time September was colder than average was in 2008. The reference period is 1981–2010.

The highest temperature of the month, 23.5 degrees, was recorded at the Tulkkila observation station in Kokemäki on 27 September. The lowest temperature of the month, -7.1 degrees was recorded at the Lompolonvuoma observation station in Kittilä on the same date.

Heavy rains in the central parts of the country

There were large regional variations in the precipitation levels. In the central part of the country as well as in Northern Ostrobothnia and Kainuu, the precipitation levels were unusually high, even exceptionally high in some places. In other parts of the country, the precipitation levels were largely lower than usual. In September, it rained most in Merikarvia, where the Tuorila observation station recorded total precipitation level of 144.1 mm. The highest level of precipitation during 24 hours, 65.6 mm, was recorded at the Petäisenniska observation station in Kajaani on 16 September. The month’s smallest precipitation, 18.8 millimetres, was measured at the Utsjoki Kevo observation station.

Slightly under 3,500 cloud-to-ground lightning strikes were observed in September, with the long-term average being 4,400.

The Aila storm caused damage especially in the western part of the country

On Aila's name day, 17 September, an exceptionally powerful storm for the time of the year passed over Finland. The low-pressure precipitation area brought heavy rainfall to the central parts of the country during 16 September, while the highest wind speeds were measured on 17 September. At the time, the 10-minute average wind at the Kylmäpihlaja observation station in Rauma reached 29.4 m/s at its highest. The highest gust value, 35,3 m/s, was measures at the Kallan observation station in Pietarsaari. In the land areas, the highest gust value, 26.8 m/s, was measured at Vaasa Airport.

Further information:

Weather statistics from the Climate Service, tel. 0600 1 0601 (€4,01/min + local charges) Weather forecasts from the meteorologist on duty 24 h/day, tel. 0600 1 0600 (3.85 €/ min + local network charge)

Weather StatisticsSeptember