What does weather 999 mean?

March 9 refers to the third cold day from the winter solstice, which is the coldest period of the year. Starting from the winter solstice, every "nine days" is counted as a "nine", the first nine days are called "one nine", the second nine days are called "two nine", and so on.

The so-called "dog days are hot, March 9 is cold", and the coldest time of the year is from March 9 to April 9. Count nine cold days, that is, from the date of the winter solstice (the anniversary of the dry branch), count 19 every nine days until 9981, when the peach blossoms bloom, the weather will be warm. There is also a saying that "1999, 1999, there are cattle everywhere". After 1999, "the spring is deep and the sun is warm", and the spring ploughing season has arrived. Because of China's vast territory, the climate varies greatly from place to place, not all over the country.