Nanchang has a monsoon-influenced humid subtropical climate with four distinct seasons. Winters are short and cool with occasional frosts; it begins somewhat sunny and dry but becomes progressively wetter and more overcast. Spring begins especially gloomy, and from April to June, each month has more than 220 mm (8.7 in) of rainfall. Summer is long and humid, with amongst the highest temperatures of any Chinese provincial capital, and with the sun shining close to 60 percent of the time in July and August, is the sunniest time of year. Autumn is warm to mild with the lowest rainfall levels of the year. The monthly 24-hour average temperature ranges from 5.5 °C (41.9 °F) in January to 29.5 °C (85.1 °F) in July, while the annual mean is 18.00 °C (64.4 °F). Annual precipitation stands at around 1,610 mm (63 in); with monthly percent possible sunshine ranging from 23 percent in March to 60 percent in August, the city receives 1,832 hours of sunshine annually in average. Extremes since 1951 have ranged from −9.7 °C (15 °F) on 29 December 1991 to 40.6 °C (105 °F) on 23 July 1961.