Oslo has a humid continental climate (Dfb according to the Köppen climate classification system). Because of the city’s northern latitude, daylight varies greatly, from more than 18 hours in midsummer, when it never gets completely dark at night, to around 6 hours in midwinter.[citation needed] Despite its northerly location, the climate is relatively mild throughout the year because of the Gulf Stream.
Oslo has pleasantly mild to warm summers with average high temperatures of 20–22 °C (68–72 °F) and lows of around 12 °C (54 °F). Temperatures exceed 25 °C (77 °F) quite often, and heatwaves are common during the summer. The highest temperature ever recorded was 35 °C (95 °F) on 21 July 1901. Due to the fjord being a relatively enclosed body of water, the water temperatures can get quite high during long warm periods. Winters are cold and snowy with temperatures between ?7 °C (19 °F) up to ?1 °C (30 °F). The coldest temperature recorded is ?27.1 °C (?16.8 °F) in January 1942.Temperatures have tended to be higher in recent years.
Annual precipitation is 763 millimetres (30.0 in) with moderate rainfall throughout the year. Snowfall can occur from November to April, but snow accumulation occurs mainly from January through March. Almost every winter, ice develops in the innermost parts of the Oslofjord, and during some winters the whole inner fjord freezes. As it is far from the mild Atlantic water of the west coast, this large fjord can freeze over completely, although this has become rare. Even for its latitude, Oslo is outstandingly cloudy, receiving a diminutive average of 1,668 hours of bright sunshine annually. Of the 4,456 possible sunshine hours that could be received annually, Oslo receives only 1,668 (37%) of that total.
