Why is there so much rainy season in March in Marcand, Sichuan?

According to central weather bureau's official website, it's monsoon season. The hot air in the south has come, and the cold air has not receded. Two air streams will collide and it will continue to rain. This is the so-called rainy season. After entering March, as the rain solar term said, there was a lot of rain, that is, on March 5, it entered the solar term of fright, and it was still raining on the day of fright. Then there are intermittent rainy days, because of the high humidity and low temperature, there is fog every day.

The region belongs to the plateau continental monsoon climate, and its main climatic characteristics are: obvious dry season and rainy season, unclear four seasons, no summer in most areas, abundant sunshine, large temperature difference and frequent windy days in dry season. The annual average temperature is 8 ~ 9℃, the annual rainfall is about 753 mm, the sunshine reaches more than 1500 hours, and the absolute frost-free period is about 120 days.