The Meteorological Institute says that daytime temperatures, on the other hand, will remain close to the long-term average.
The warmest time of day is currently around 3-5 degrees above zero in the south, or around zero in parts of the north.
The icy conditions could even bring snow to southern regions towards the end of next week. Although the forecasts are uncertain, the south's dry spell is currently expected to last until Thursday, before snow hits on Friday.
Lapland can also expect a small amount of fresh snow.