Waterways now have some ice cover even in the south of Finland, but it remains treacherous in most places. Ice expert Jouni Vainio of the Finnish Meteorological Institute (FMI) says that the ice situation remains poor even though temperatures in the south have dipped below freezing point in recent weeks.
"South of a line running from Vaasa to Lappeenranta, lakes and rivers are only just beginning to freeze," said Vainio.
According to Vainio ice cover could also be weak further north, thanks to the generally mild winter so far. Speaking on Yle's morning television programme Aamu-TV, he said that northern regions of the country, and northern parts of central Finland, should have ice strong enough to walk on.
Vainio says that snow cover is hampering the work of assessing the strength of lake and sea ice. According to Vainio the most dangerous points are where water is moving underneath the ice.
[Story continues after graph]
A few centimetres of ice cover should in principle be enough to support a human walking on the surface, but natural ice is never even. Ice that is thick on the shoreline is often weaker further from the shore.
"For movement on ice cover to be safe, there should be at least 10 centimetres of ice," said Vainio.
At sea the ice situation is much worse than normal. The Bay of Bothnia has only relatively thin ice cover, close to the shore.