When is the ground first covered with snow and when is it permanent?
In Finland the first snow cover is consired to have happened on the day when there is measurable snow in the morning observation (06 UTC). The permanent snow cover is defined as the longest period with consecutive snow cover days.
The very first snowflakes fall to the ground in late August or early September over the higher peaks in Lapland. The first ground-covering snow and permanent snow cover arrive at different times in different parts of the country. In Lapland the winter is long (approximately seven months) and the permanent snow cover comes significantly earlier than in southern Finland.
The snow cover is usually thickest in mid March, in Lapland often as late as early April. Soon after that the snow cover starts to melt fast.
Maximum snow depth and the number of snow cover days
The maximum snow depth is usually found around March (most of the country) or early April (Lapland). Typically the ground is covered with snow over half a year in Lapland.