Driving conditions have worsened on Sunday morning in southern and central parts of the country, Fintraffic warns.

Falling and blowing snow coupled with slippery surfaces due to rising temperatures have caused poor road conditions through much of the country, from North Karelia across the south to the Åland Islands.

A Ukrainian bus full of passengers drove into a ditch in Ii, Northern Ostrobothnia, on Sunday morning, police said. The accident occurred at the Asemantie roundabout on national road 4 between Oulu and Kemi. No serious injuries were reported.

Wind chill and frazil ice

The severe chill in northern Finland is set to ease slightly on Sunday. In the south, the weather has been getting milder since yesterday.

Temperatures are expected to rise to between -7 and -14 degrees Celsius in the south, but the wind will make it feel colder. In Lapland, temperatures will vary between -24 and -40 degrees Celsius.

There are also warning of gusty winds and very rough waves on most sea districts, and warnings of local flooding throughout central and northern Finland due to frazil ice crystals building up on rivers and other waterways.

Thousands of tourists wait in Kittilä as temps hover around -40C

Meanwhile Finnair has cancelled all flights to and from Kittilä, Finnish Lapland, on Sunday, due to severe cold. Fifteen international and 8 domestic flights were scheduled to depart from the airport on Sunday.

One flight from Helsinki Airport to Rovaniemi and back has also been grounded.

On Saturday, the flag carrier scrubbed several flights to and from northern Finland. Airport operator Finavia told the Finnish news agency STT that there were no flights in or out of Kittilä Airport on Friday or Saturday.

Thousands of foreign tourists are awaiting updates about the status of their return flights.

On Sunday morning, the temperature at Kittilä Airport was -37 degrees Celsius. The temperature in Kittilä has been below -35 degrees Celsius for several days, which hampers de-icing of aircraft, among other operations.

The deep freeze is expected to continue in the Kittilä region on Monday, when the Finnish Meteorological Institute predicts temperatures of almost -40.

"In addition to the severe cold, there is moisture in the air, especially in the Kittilä area, which is exceptional at such low temperatures. The severe frost and moisture in the air intensify the effects caused by the weather," Finavia said in a statement, warning of possible cancellations at Kittilä and Rovaniemi airports through Monday, adding that "decisions to cancel flights are always made by airlines".

"For companies operating on the apron in particular, the current weather conditions and temperatures of around -40 degrees Celsius can cause challenges. In concrete terms, this is seen, for example, in the fact that connectors on maintenance, ground handling and refuelling equipment freeze and doors and hatches on ground equipment freeze easily," Finavia explained.

Flights at other airports in Lapland have been operating mostly normally.