What does the sentence "the autumn equinox is windy in the northwest, and the twelfth month is unclean in winter" mean?

As the saying goes, "the autumn equinox is windy in the northwest, and the winter in the twelfth month is not clean", which I personally understand literally. After the autumnal equinox, the weather began to change, and the northwest wind began to blow, and the weather gradually became cold, that is, there would be snow in the twelfth month. In fact, in this area of my home, if the weather is like this, this crop will have a bumper harvest in the coming year, which actually means a bumper harvest in the coming year.

There is an old saying that "the autumn equinox is windy in the northwest, and the twelfth month is unclean in winter", which means that with the continuous alternation of the four seasons, the northwest wind gradually prevails, and the weather is about to enter the late autumn, with a westerly wind and continuous rain. When the farmland is sown, that is, around the National Day, this is the key period for sowing winter wheat! "Winter is not clean in December" and "winter is not clean" means that it often rains and snows in December. And a rainy and snowy year is also a reminder of the bumper harvest in the coming year!

Our previous life was really hard and the conditions were not good. In the past, because there was no weather forecast, rural people depended on the weather for their meals and rain for their irrigation. Old people summed up many agricultural proverbs through their life and work experience, which became the most concerned by everyone on special days. This "autumn equinox, northwest wind, December and winter are unclean" means that the weather conditions in autumn have a great influence on the future weather. But the "dirty winter in the twelfth month" here means that there will be snowy and windy weather in the twelfth month. It's really a good sign that there is much snow in December in winter. If you are in the southwest, the villagers will definitely explain the bumper wheat harvest in 2008.

However, I think these crop proverbs and sayings still have some essence, which can be used for reference. After all, my family has never planted land.