Meishan city is located in the middle and low latitudes, located in the west of Sichuan Basin and the middle reaches of Minjiang River. It is characterized by the alternation of sea land monsoon every year. It has four distinct seasons, mild climate, abundant rainfall, hot and rainy season, less sunshine and long frost free period. There is no severe cold in winter, less frost and snow; there is no hot summer in summer, which is the frequent occurrence period of rainstorm and other severe convective weather; the warming in spring is early, and the precipitation is less; the autumn is warm and cool, with more continuous rain. The annual average temperature is 16.8 ℃; from July to August, the hottest month is 25.7 ℃ and 25.6 ℃; the extreme maximum temperature is 39.9 ℃ (August 12, 2006, Renshou); January is the coldest with an average temperature of 6.5 ℃, and the extreme minimum temperature is minus 4.2 ℃ (Hongya, December 28, 1991). The highest monthly average temperature is 28.4 ℃ (August), and the lowest is 3.8 ℃ (January). The frost free period is 308-320 days. The annual average sunshine duration is 1060-1300 hours, which is one of the low sunshine areas in China. The annual average precipitation is 1153.7mm, the annual average rainfall days is 159 days, the maximum is 228 days (Hongya, 1989), and the minimum is 116 days (Renshou, 2003 and 2006). The maximum annual rainfall is 2165.4 mm (Hongya, 1966), and the minimum rainfall is 544.4 mm (Renshou, 2006). Hongya, Danling in the West and Qingshen in the South have abundant annual rainfall, which is one of the rainstorm centers in the whole province: Renshou County in the East has higher drought frequency than other districts and counties in the city. In the annual flood season (May to September), the rainfall is the most in July, accounting for about 85% of the total annual rainfall. The annual average days of gale greater than 6 are 5 days. The annual average thunderstorm days are about 30 days. In addition, with the increase of altitude in the southwest mountainous area, there is a complete climate belt spectrum from the subtropical warm temperate zone to the cold temperate zone and the vertical climate difference (stereoclimate).