Nine Periods Following the Winter Solstice
In Chinese tradition, the coldest days of the year are the 81 days after the Winter Solstice. These 81 days are divided into nine periods following the Winter Solstice. The origin of the nine periods following the Winter Solstice is unconfirmed, but it has been widely used at least since the Northern and Southern Dynasties (420-589). In Chinese, people call the nine periods "Shujiu", which literally means counting to nine. The weather usually gets warmer after these 81 days.
Natural law of the nine periods following the Winter Solstice
The nine periods following the Winter Solstice are summarised according to the 24 solar terms. The coldest periods are the third and fourth, which fall around the "Major Cold" solar term. There are many chants and poems that offer an explanation in the change of the weather over the nine periods following the Winter Solstice. For instance, in Beijing people say "During the first and second period, hide the hands in sleeves; the third and fourth period, walk on the icy river; the fifth and sixth period, enjoy the sight of sprouted willows along the river; the seventh period, rivers unfreeze; the eighth period, swallows come back from the South; nine days after the ninth period, farming becomes active".
There are also many proverbs about the nine periods following the Winter Solstice. For instance, people say "if the first period is warm, then the following periods will be especially cold"; or "by the third period ice turns very solid"; or "The end of the nine periods is the time to enjoy the peach blossom".
Customs during the nine periods following the Winter Solstice
During the Ming Dynasty, people enjoyed "drawing the nine periods", which was a way to pass by the coldest time. On the Winter Solstice, people often draw a Chimonanthus (wintersweet) branch with nine blossoms each with nine hollow petals, (totalling 81 petals). Each day one would colour one petal and the coldest days of the year would have passed when the drawing is complete.
In the Qing Dynasty, "writing the nine periods" became a popular activity. Obviously, it means choosing nine Chinese characters that each have nine strokes. Each day one stroke would be written from the beginning of the Winter Solstice. This way, the coldest days of a year would have passed when the characters have been written completely. There are two commonly used sentences: "亭前垂柳珍重待春風", which means "Take good care of the weeping willows in front of the pavilion and wait for the Spring breeze"; and "春前庭柏風送香盈室", meaning "Near the Spring, wind blows the cypress in the courtyard and fills the room with fragrance". Moreover, apart from making the stroke, some people like to record the weather condition of each day, so the "writing of the nine periods" actually also becomes a specific meteorological record.