The conditions for the creation of an ice wall on the lake occur about once a decade, when the ice is thick enough and there are large variations in the daily temperatures. As the ice melts, it creates a chasm, but when it freezes again and expands, it forces the edge of the chasm upwards, creating the 'wall' effect.

Gusty winds and precipitation began pounding Finland from the southwest on Wednesday morning.

After several warm days, lightning bolts struck Finland about 16,000 times on Saturday. By evening, nearly 20,000 customers were without electricity. More trees may be felled as electrical storms move toward the Russian border.

Record wind speeds have been clocked in southern maritime districts as a storm dubbed Aapeli causes widespread power cuts and train delays across Finland.

The Central Finland town of Jyväskylä has had a sum total of 4.5 hours of sunshine so far in November.

The Finnish Meteorological Institute has issued a warning of very cold temperatures from Monday afternoon to Wednesday morning, February 26 to 28.