2. first frost is the eighteenth of the twenty-four solar terms and the last solar term in autumn. At this time, the solar ecliptic is 210; Every year Gregorian calendar1October 23rd-24th. First frost doesn't mean "frost", but it means that the temperature drops suddenly and the temperature difference between day and night is large. In first frost season, everything is finished, and it begins in the morning, and the sun goes down to the ground, and the yin qi begins to condense, and the weather is getting colder in first frost. After the solar terms in first frost, the scene of late autumn is obvious, and the cold air goes south more and more frequently.
3. As far as the national average is concerned, first frost is the season with the largest temperature difference between day and night in a year. First frost solar terms are characterized by cold weather in the morning and evening, hot weather at noon, large temperature difference between day and night, and obvious autumn dryness. First frost doesn't mean that it will "frost" when entering this solar term. In fact, "frost" doesn't fall from the sky, and it is formed by the condensation of water vapor on the ground when it meets cold air due to temperature difference.