Under the Köppen climate classification, Harbin features a monsoon-influenced, humid continental climate (Dwa). Due to the Siberian high and its location above 45 degrees north latitude, the city is known for its cold weather and long winter. Its nickname Ice City is well-earned, as winters here are dry and freezing cold, with a 24-hour average in January of only −17.6 °C (0.3 °F), although the city sees little precipitation during the winter and is often sunny. Spring and autumn constitute brief transition periods with variable wind directions. Summers can be hot, with a July mean temperature of 23.1 °C (73.6 °F). Summer is also when most of the year’s rainfall occurs, and more than half of the annual precipitation, at 538 millimetres (21.2 in), occurs in July and August alone. With monthly percent possible sunshine ranging from 52 percent in December to 63 percent in March, the city receives 2,571 hours of bright sunshine annually; on average precipitation falls 104 days out of the year. The annual mean temperature is +4.86 °C (40.7 °F), and extreme temperatures have ranged from −42.6 °C (−45 °F) to 39.2 °C (103 °F).