 On average, winter lasts from early January to late February in the outermost islands in the archipelago and the warmest locations along the southwestern coast – notably in Hanko, and from early October to mid May in the most elevated locations, such as northwestern Lapland and the lowest valleys in northeastern Lapland.This means that southern portions of the country are snow-covered about three to four months of the year, and the northern for about seven months.The long winter causes about half of the annual precipitation in the north to fall as snow.