An electrical storm system is arriving in Finland from the west on Wednesday afternoon, bringing along with it plenty of heavy rain showers and strong winds.

The Finnish Meteorological Institute told news agency STT that thunderstorms are set to start at two or three in the afternoon as the storm makes landfall between the cities of Pori and Vaasa.

The most violent thunderstorms and heaviest rainfall is likely to be concentrated in the western part of the country, with the system moving eastward by the evening.

"In Eastern Lapland and Kainuu, it will almost certainly rain and thunder at night at the latest," said Yle meteorologist Elias Paakkanen.

Warning issued for all of Finland

A warning has been issued across the entirety of Finland for extremely violent thunderstorms for the next 24 hours. The wind speed is forecast to be over 25 metres per second, along with aforementioned heavy rains, amounting to more than 30 millimetres per second in some areas, according to Paakkanen.

"Boaters in all areas of the sea are also warned of the thunderstorms," Paakkanen emphasised.

A severe thunderstorm battered Oulu Tuesday evening, leaving in its wake flooded streets and chaotic traffic. Rescue services answered nearly 100 calls related to the thunderstorm on Tuesday evening.