What festival is closest to the first frost?

Early winter is closest to the first frost.

In the first frost season, it's all over. From the morning, the sun went down to the ground, Yin Qi began to condense, and the first frost weather became colder and colder. Because "frost" is a manifestation of cold weather and large temperature difference between day and night, it is named "first frost", which means "sudden drop in temperature and large temperature difference between day and night". The 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.

The first frost is the last solar term in autumn and the transition from autumn to winter. In the first frost season, everything is finished, everything goes to heaven, the sun goes to the ground, and the yin begins to condense. The cold weather began with the first frost. Yizhoushu Zhou said: "Autumn and March are empty: summer, autumn equinox, first frost."

In Lun Heng, Wang Chong of the Eastern Han Dynasty said: "Clouds and fog are also signs of rain, while summer is dew, winter is frost, temperature is rain, cold is snow, and rain and dew are frozen, all from the ground, not from the sky." Whether it is dew or frost, "it comes from the ground, not from the sky." How can it be called first frost? In fact, the name "first frost" is just a metaphor.

Because "frost" is a manifestation of cold weather and large temperature difference between day and night, it is named "first frost" to indicate that "the temperature drops suddenly and the temperature difference between day and night is large".