79 rivers open and 99 geese come. What's the matter with the weather getting better and better?

79 rivers open and 99 geese come. The weather is getting warmer and warmer.

"Seven or nine rivers open, eight or nine geese come" means that from the winter solstice, sixty-three days will be the day when the river thaws, which means that the weather has begun to warm up slowly. "August 9 geese come" means that the geese began to fly back from the south on the 72nd day.

Calculation method of the number nine

The method of calculating cold and warm by number nine is suitable for areas where the temperature changes obviously from winter to around in China. The calculation of temperature and warmth changes is accurate to days. Judging from the number of days from winter to Sunday, the coldest periods are "March 9 and April 9", while counting to "998 1 day" is a warm day in late spring.

There are also some places where the number 9 is counted from the day of the winter solstice. In some cold areas, the temperature in winter and spring is below zero degrees Celsius for a long time, and the temperature changes are not obvious from winter to around. "Nine days" is not much different from the temperature.