Yangzhou features a humid climate being in the subtropical zone, and its annual average temperature is 15�C. In July, the average temperature is 27.6�C. The coldest month is January, with an average temperature of 1.5�C. The frost-free season is about 222 days, and its duration of yearly sunshine is about 2,176.7 hours. The annual average precipitation is 1,030 mm, and about 45 percent of rainfall is concentrated in the summer. The rainy season known as "plum rain season" usually lasts from mid-June to late July. During this season, the plums are ripening, hence the name plum rain.