When does the weather usually get warmer?

The weather will begin to improve after the Ninth Five-Year Plan. The solar term in beginning of spring is May 9th, and the general weather began to improve after beginning of spring.

The temperature is low during March 9 and April 9, but this cold weather won't last long. After May 9th, the weather will get warmer. Proverbs: "Walk on the ice in March 1949, and see the river willows in May 1969." This is what I'm talking about. By May 9th, the climate will be warmer, and then it will make a smooth transition to warm spring weather.