Winter goes and spring comes.

Beginning of winter thunders against spring, which means it thunders and rains in beginning of winter, as if spring is coming.

Before and after winter, precipitation in most parts of China decreased significantly. At this time, the water condition is closely related to the seedling growth and overwintering of crops. If there is a lot of precipitation (it usually rains when it thunders), it doesn't mean that spring has come, but now the solar term is beginning of winter, so there is a saying that "beginning of winter thunders against spring".