When did the weather start to get hot?

Every year, the Gregorian calendar 65438+ starts counting nine on the second day of the winter solstice on February 22nd. Liang Chaozong Ba wrote in the Chronicle of Jingchu: "The number of winter solstice days and 998 1 day are the end of cold." Count nine cold days, that is, from the solstice of winter, count a "nine" every nine days until the "99" of 81 days, and the weather will warm up.

From February 23rd of 18, the middle of March is 8 1 days later.