There are two explanations for the phrase "early autumn, late autumn". Some people think it refers to the date in beginning of autumn, while others think it refers to the date in beginning of autumn.

First of all, the ancients set up 24 solar terms to guide agricultural production. These 24 solar terms correspond to the lunar calendar. Beginning of autumn is one of the 24 solar terms. In the Gregorian calendar, it is probably August 7 or 8 every year. However, in the lunar calendar, the corresponding time is quite different. Some beginning of autumn will appear in June of the lunar calendar, that is, early autumn. Beginning of autumn will appear in the seventh month of the lunar calendar at the latest, which is called late autumn. Between early autumn and late autumn, there can be a difference of more than one month at most.

The solar terms in beginning of autumn mostly appear between June and July in the lunar calendar, so people gradually compare the coolness and heat in July in the lunar calendar through the morning and evening in beginning of autumn. In fact, if beginning of autumn is in early June, then the July of the lunar calendar is completely after beginning of autumn, so it will be cooler. If the lunar calendar returns to beginning of autumn in July, then beginning of autumn will be late, and then July will only belong to beginning of autumn for ten days. If it stays in dog days for more than half a month, it will be very hot.

This is the scientific basis of "beginning of autumn is cold in the early stage and beginning of autumn is hot in the later stage". A few days ago this year was the eighth day of the seventh lunar month in beginning of autumn, which belongs to late autumn, which means it will be hot for some time this year.

Besides, the second argument is that early autumn and late autumn don't look at the date, but in beginning of autumn. If it is early autumn morning, autumn is cool. If beginning of autumn time is in the afternoon, it will be hot for a while. Beginning of autumn this year is on August 8th at 3: 12. According to this idea, it belongs to early autumn and will be very cool.

However, meteorologists believe that the main factors affecting the weather are atmospheric circulation, solar radiation and human production activities, and it is scientifically untenable to judge the temperature and temperature according to beginning of autumn time.