Xi 'an belongs to temperate zone.

Xi 'an Plain belongs to warm temperate semi-humid continental monsoon climate, with four distinct seasons: cold, warm, wet and dry, cold in winter, light breeze, foggy and little rain and snow. Spring is warm, dry, windy and the climate is changeable; Summer is hot and rainy, drought is prominent, and there are many thunderstorms and strong winds; Autumn is cool, the temperature drops rapidly, and the autumn rain is obvious. Xi belongs to warm temperate semi-humid continental monsoon climate. Four distinct seasons, hot and rainy in summer, cold and little rain and snow in winter, and even rainy weather in spring and autumn.

The average annual temperature in Xi 'an and suburban counties is between13.1~13.4℃. The annual extreme maximum temperature is 35 ~ 465438 0.8℃; The extreme minimum temperature is minus 16 to minus 20℃. July is the hottest month in the whole year, with the monthly average temperature of 26. 1 ~ 26.3℃ and the monthly average maximum temperature of about 32℃. 65438+ 10 is the coldest month, with the monthly average temperature of -0.3 ~- 1.3℃, the monthly average minimum temperature of -4℃ or so, and the annual variation is 26-27℃.

The precipitation changes greatly during the year, and there is a great difference between rainy and dry years, with the maximum of 590 mm, and the seasonal distribution of precipitation is extremely uneven. 78% of the rainfall is concentrated in May to 10, of which July to September accounts for 47% of the annual rainfall, with occasional heavy rain. The annual average relative humidity is about 70%. The annual average wind speed is 1.8m/s, and the dominant wind direction throughout the year is northeast wind.

Geographical location of warm temperate zone:

The topography of the warm temperate zone gradually declines from west to east, from plateau mountains to plain hills. Due to the influence of topography, the whole zone is also divided into four natural regions: Shandong Peninsula and Liaodong Peninsula, North China Plain, Loess Plateau and Hebei-Liaoning Mountain.

Because it is located at the edge of the mid-latitude westerly belt and the eastern monsoon area, the climate in this area is humid and semi-humid. Although it is cold in winter, winter wheat can be planted and crops can be harvested three times a year. In the south, warm crops such as cotton and sweet potato can also be planted. Deciduous fruit trees such as apples, peaches, apricots, walnuts, chestnuts and jujubes can survive the winter safely without protection.

The unfavorable climatic conditions are mainly cold in winter, little rain and snow, and dry and windy in spring. Autumn is crisp and sunny, which is the tourist season. The Yellow River, Huaihe River and Haihe River, the three major rivers in northern China, are all major local rivers and are all called "harmful rivers".

Among them, the Yellow River is famous for its rich sediment, and the long-term siltation has made the lower reaches of the Yellow River a world-famous "river on the ground". The middle and upper reaches of the Yellow River flow through the sandstorm area and the loess plateau with serious soil erosion. Under the double erosion of wind erosion and water erosion, the annual sediment input into the Yellow River is 65.438+0.6 billion tons, which is the highest in the world.

The shortage of water resources is a common problem in the improvement of ecological environment. Due to the long-term development and destruction of human beings, almost all the natural vegetation in this area has disappeared, and soil erosion in the Loess Plateau and desertification in the northern marginal areas have become the most serious ecological problems in China. Preventing desertification from spreading to Beijing has become one of the global ecological issues of international concern.