Which solar term is the coldest?

Slight cold is the 23rd solar term in the Lunar New Year. Before and after the slight cold, the sun reached 285 degrees of the yellow meridian, which was the coldest period in winter in China, so it was called "Sanjiu Cold".

Although it has the word "small", the coldest solar term is slight cold rather than great cold. Although the light around the winter solstice is the most oblique, since summer, the accumulated heat on the earth's surface can supplement a lot of heat loss. During the slight cold, the required heat and the released heat tend to be equal, that is, the surface layer stores the least heat. So the weather is the coldest in the slight cold solar terms. This is similar to the reason why the highest temperature in a day does not appear at noon but around 2 pm. After the slight cold, the temperature gradually rises, so the average temperature of the great cold is slightly higher than that of the slight cold.

There is a saying in Minnan proverb that "a slight cold freezes, and it is cold enough to lift the fire cage." It shows that even in the southern region, the slight cold solar terms are very cold. It's normal for the solar terms to be a little chilly. If the weather is cold, pests will freeze to death. Therefore, there is also a proverb that "six animals are safe after a slight cold".