Is the weather in Yunnan good in September?

The climate of Yunnan Province has seven temperature zone climate types: northern tropical zone, southern subtropical zone, central subtropical zone, northern subtropical zone, warm temperate zone, mid-temperate zone and plateau climate zone. Yunnan's climate has the characteristics of low-latitude climate, monsoon climate, and mountain climate. Its main manifestations are:

Regional differences and vertical changes in climate

Yunnan's latitude and altitude are related. In terms of latitude, its location is only equivalent to the geographical latitude from Leizhou Peninsula to Fujian, Jiangxi, Hunan and Guizhou. However, due to the terrain being higher in the north and lower in the south, the height difference between the north and the south is as high as 6663.6m, which greatly aggravates the problems within the province. Temperature differences caused by latitude factors. This combination of high latitude and high altitude, low latitude and low altitude is consistent, that is, the increase in latitude in the horizontal direction coincides with the increase in altitude in the vertical direction. As a result, the annual average temperature in various places, except for the Jinsha River Valley and Yuanjiang River Valley, generally increases from north to south. The average temperature is about 5 to 24°C, and the temperature difference between the north and the south is about 19°C.

Due to the influence of terrain and different weather systems, special situations often occur in the latitudinal distribution of temperature in the province, and the phenomenon of "hot in the north and cool in the south" occurs. Especially in terms of vertical distribution, because the territory is mountainous, the erosion of river beds continues to deepen, forming high mountains and deep valleys. From the valley to the top of the mountain, there are differences in climate types caused by the increase in height. Generally, the temperature decreases for every 100m the plateau rises. About 0.6℃.

The annual temperature difference is small, but the daily temperature difference is large

Because it is located on a low-latitude plateau, the air is dry and relatively thin. The amount of solar heat received in various places varies with the change of the sun's altitude angle. In addition to increases and decreases, it is also affected by clouds and rain. In summer, the average temperature on the hottest day is around 19-22℃; in winter, the average temperature on the coldest month is above 6-8℃. The annual temperature difference is generally 10 to 15°C, but the temperature is lower on rainy days. The temperature changes throughout the day are cool in the morning and hot in the afternoon. Especially in winter and spring, the daily temperature difference can reach 12-20℃.

Precipitation is abundant, dry and wet, and unevenly distributed

The annual precipitation in most areas of the province is 1100mm, and in some southern areas it can reach more than 1600mm. However, because winter and summer are controlled and affected by different atmospheric circulation, the distribution of precipitation in seasons and regions is extremely uneven. In winter, it is located on the west side of the "Kunming Quasi-stationary Front" and is controlled by a single warm air mass, with little precipitation. Affected by the southwest monsoon, summer is humid and hot with abundant rainfall. The maximum amount of precipitation occurs in June to August, accounting for about 60% of the annual precipitation. The winter and spring seasons from November to April are the dry season, with precipitation accounting for only 10-20% of the whole year. Yunnan has a long frost-free period. The southern border is frost-free all year round; the frost-free period in Wenshan, Mengzi, Simao, Lincang, Dehong and other places in the south is 300 to 330 days; the frost-free period in Kunming, Yuxi, Chuxiong and other places in the central part is about 250 days; the colder Zhaotong and Di Qingda 210~220 days. The amount of sunlight in Yunnan ranges from 90 to 150 kcal per square centimeter per year.