Helsinki has a hemiboreal humid continental climate. Owing to the mitigating influence of the Baltic Sea and Gulf Stream, temperatures in winter are much higher than the far northern location might suggest, with the average in January and February around −5 °C (23 °F). Temperatures below −20 °C (−4 °F) occur normally a week or two in a year. However, because of the latitude, days last less than six hours around the winter solstice with really low sun rays, and the very cloudy weather at this time of year accentuates the darkness. Conversely, Helsinki enjoys long days in summer, close to nineteen hours around the summer solstice. The average maximum temperature from June to August is around 19 to 21 °C (66 to 70 °F). Due to the marine effect, especially in the summer daily temperatures are cooler and night temperatures are higher than further away in the mainland. As near as in Vantaa, the climate is surprisingly much more continental, with warmer summers and colder winters. The highest temperature ever recorded at city centre was 33.1 °C (91.6 °F) on 18 July 1945 and the lowest was −34.3 °C (−30 °F) on 10 January 1987
