"Easternmost Finland may get 10 cm on Friday," says Yle meteorologist Matti Huutonen.
The first snow was recorded in the morning in the cities of Jyväskylä and Kuopio, where 2 cm had fallen by 9 am.
The Finnish Meteorological Institute (FMI) defines the first snowfall as at least one centimetre of snow on the ground at 9am at one of its weather stations. Huutonen says that Eastern Finland's first snow came about a week earlier than usual. Northern Lapland received its first snow on Sunday.
Slippery roads, especially in the east
The FMI warns of poor road conditions through most of eastern Finland from Friday afternoon through at least midnight due to snow or sleet, with "very bad" conditions in North Karelia.
"The further west you go, the wetter the snow is. Overnight frost will make road surfaces slippery, so those driving on summer tyres must be careful," says Huutonen.
Kainuu, North Savo, South Savo and South Karelia may get 1-5cm of snow, he adds.
Chilly October weather in store
Precipitation is expected through Friday evening, but it should be mostly over by Saturday. Conditions will remain cool, though.
"Cold air is moving in from the north, so all of next week will be chilly. Temperatures in the south will be 5-6 degrees colder than usual for this time of year," Huutonen says.
Overnight readings will drop below freezing throughout the country, ranging from a couple of degrees below zero down south to -10 degrees Celsius in parts of Finnish Lapland.