"On August 15th, Yun Zheyue, it snows and lights on the 15th day of the first month" is an agricultural proverb circulating in China. It is the weather forecast experience summarized by the working people in our country in the long-term production practice, which reflects the echo relationship between holiday weather. It means that on the Mid-Autumn Festival on the fifteenth day of the eighth lunar month, if the sky is overcast and there is no full moon, then the fifteenth day of the first month of next year will be cloudy or snowy.

Mid-Autumn Festival is a traditional folk festival in China. As the saying goes, the Mid-Autumn Festival is especially bright. On the night of Mid-Autumn Festival, the bright moon is in the sky, and the silver light shines on the earth. On this pleasant and quiet night, people get together to watch the bright moon and tell children the fairy tales of the Goddess Chang'e flying to the moon, osmanthus tree and Jade Rabbit. If dark clouds cover the moon and the sky is gloomy, it will be disappointing! But it means that another traditional festival in China, Lantern Festival, is full of snowflakes and exciting when every household is decorating.

The echo relationship between the weather of these two traditional festivals has always been concerned by people. Over time, in many places, if the sky is covered with dark clouds on the night of August 15, then snowflakes often fly on the first month 15. So people summed up a popular weather proverb: "August 15th, Yun Zheyue, the 15th day of the first month, bright".