Finland is a land of extremes. In 2010, for example, the highest temperature was 37.2ºC (99ºF), and the lowest temperature was -41.3ºC (-42ºF).
The fact that Finland is 1,157km long at its maximum means that the weather can be very different in the north of the country than it is in the south. In fact, above the Arctic Circle there are 8 distinct seasons, each with its own distinct type of daylight, temperatures, and natural phenomena. These seasons are known as Christmas, Frosty Winter, Crusted Snow, Ice Breaking, Midnight Sun, Colourful Autumn, and First Snowfall. Southern Finland also distinctive seasons, but they are the traditional Spring, Summer, Autumn, and Winter.
Finland is famous for being the land of the Midnight Sun. In Lapland a single summer day can last over two months, for example in Utsjoki, which is at a latitude of 69°52', the sun doesn't set between May 16th and July 27th, and in Rovaniemi, which is at a latitude of 66°30', the sun doesn't set between June 6th and July 7th. Even in the south at midsummer the sun is still shining at 10pm, and is likely to be already up when revellers are leaving the clubs in the early morning. Night itself is somewhat of a misnomer, darkness doesn't really fall, instead there is a period of prolonged dusk which fades to twilight. Summer temperatures are usually even, often reaching the mid thirties in August, and the extended days mean that the lakes are perfect for swimming in from the end of June onwards.
Winter is conversely dark and cold, and the mean temperature remains below 0°C. Winter usually begins in mid-October in Lapland, and during November in the rest of Finland, although in the southwestern archipelago it doesn't begin until December. It is the longest season, lasting for about 200 days in Lapland and about 100 days in southwestern Finland. North of the Arctic Circle this period is known as Polar Night, although Finns are more likely to refer to it by the far more poetic term 'Kaamos', which translates as The Dark Time! In Utsjoki the Polar Night lasts from November 25th to January 17th, and even in Rovaniemi there is barely more than two hours of sunlight for the entire month of January. Permanent snow falls about two weeks after winter begins, and is deepest around mid-March, with an average of 60 to 90cm in eastern and northern Finland, and 20 to 30cm in southwestern Finland.