"Is it going to be cold or not? Look at the weather early on July 21st." Tomorrow is July 21st. Is it going to be a cold winter this year?
If it rains on July 21, it may mean a cold winter; if it is sunny and hot, it may mean a relatively mild winter.
July 21st is a day used by ancient people to predict the cold and warmth of winter. There are many agricultural proverbs used to describe the weather conditions on this day and use them to judge whether the coming winter will be cold or warm.
There is an old farmer's proverb: "On July 21, it rains and there are three layers of snow." Through long-term observation and recording of the natural environment, the ancients discovered that if it rained on the 21st of the seventh lunar month, snowfall would occur frequently during the next 3949 years, indicating that a cold winter was coming.
The cold winter is very beneficial to the safe overwintering of overwintering crops, and the cold snowy weather can also freeze bacteria and insect eggs in the soil, reducing the occurrence of diseases and insect pests in the coming year. In addition, snowy winters can also alleviate drought in spring and facilitate the growth of crops. Therefore, ancient farmer families hoped for a cold winter to ensure a good harvest.
There is also an agricultural proverb that says: "It's hot on July 21st, so you can wear single clothes in the twelfth lunar month of winter." It won't be too cold, it will be a relatively warm winter. In addition, there are similar proverbs, such as "Twenty-one, sunny and hot, warm until the end of the year" and so on. These proverbs don't mean that winter will be warm enough to wear separate layers, just that it will be relatively warmer than a typical year.
The reason why the seventh month of the lunar calendar is the "No" hexagram
The ancients designed twelve news hexagrams based on the twenty-four solar terms of the lunar calendar. The two solar terms are one hexagram. The months are expressed by Zi, Chou, Yin, Mao, Chen, Si, Wu, Wei, Shen, You, Xu, and Hai. According to the changes in the angle of the sun throughout the year, that is, the changes in yin and yang, 12 hexagrams were selected. Represents 12 months.
July is Shen Yue and is the "No Gua". It should be noted that July and Shen Yue are only roughly the same time. July starts with the first day of the lunar month, while Shen Yue starts with the beginning of autumn. The solar terms are the beginning. The hexagram image of "No" is composed of three lower lines and three upper Yang lines. The three yin lines below grow one by one from the summer solstice. By July, there are three yin and yang lines each.
"Fu Gua" has yang on the top and yin on the bottom. The qi from the sky cannot come down, and the qi from the earth cannot go up. In this way, the yin and yang do not interact, and the growth of plants slowly stops, and autumn begins. At this time, the fruits of spring growth and summer growth must be collected and prepared for winter storage. This is the "Fu Gua" in July in the four seasons. meaning.
Although "Pi Gua" means that growth will stagnate in autumn, spring will grow and summer will grow. Only with the previous round of autumn harvest and winter storage can the next round of life cycle begin. In addition, the seventh month of the lunar calendar is also an important time node for the transition between summer and autumn in the second half of the year. Therefore, the weather changes in the seventh month of the lunar calendar were also valued by the ancients.