Chongqing has a humid subtropical climate , bordering on a monsoonal humid subtropical climate and for most of the year experiences very high relative humidity, with all months above 75%. Known as one of the “Three Furnaces” of the Yangtze River, along with Wuhan and Nanjing, its summers are long and among the hottest and most humid in China, with highs of 33 to 34 °C (91 to 93 °F) in July and August in the urban area. Winters are short and somewhat mild, but damp and overcast. The city’s location in the Sichuan Basin causes it to have one of the lowest annual sunshine totals nationally, at only 1,055 hours, lower than much of Northern Europe; the monthly percent possible sunshine in the city proper ranges from a mere 8% in December and January to 48% in August. Extremes since 1951 have ranged from −1.8 °C (29 °F) on 15 December 1975 (unofficial record of −2.5 °C (27 °F) was set on 8 February 1943) to 43.0 °C (109 °F) on 15 August 2006 (unofficial record of 44.0 °C (111 °F) was set on 8 and 9 August 1933).
Chongqing, with over 100 days of fog per year, is known as the “Fog City” (雾都); this is because in the spring and fall, a thick layer of fog enshrouds it for 68 days per year. During the Second Sino-Japanese War, this special weather possibly played a role in protecting the city from being overrun by the Imperial Japanese Army.
As exemplified by Youyang County below, conditions are often cooler in the southeast part of the municipality due to the higher elevations there.