Three cold days and four warm days

This is a phenomenon in which three consecutive cold days in winter are followed by four or so relatively warm days, resulting in repeated cycles of cold and warm weather. It is a proverb used in northern China and the Korean peninsula. Because the cold in winter is largely determined by wind speed, this cycle also occurs depending on the strength of the winds blowing out from the Siberian high pressure system. The three cold days and four warm days are not very evident in the weather on the Japanese mainland, occurring perhaps once a winter. This is because the winter weather around Japan is influenced not only by the Siberian high pressure system but also by the Pacific high pressure system, which makes the weather changes more complex.

In haiku, it is simply called "sankan" or "shion," and is a winter seasonal word along with "shion biyori."

[Nemoto Junkichi]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

冬期に寒い日が3日ぐらい続くと、そのあと比較的温暖な日が4日ぐらい続き、寒暖が繰り返される現象。中国北部や朝鮮半島でいわれる俚諺(りげん)である。冬の寒さは風速に支配される部分が大きいから、このような繰り返しはシベリア高気圧から吹き出す風の強弱によっても現れる。三寒四温は日本の本土の天候にはあまりはっきりとは現れず、ひと冬に1回あるかないかという程度である。これは、日本付近の冬の天候が、シベリア高気圧だけでなく、太平洋の高気圧の影響を受け、天候の変化の様相が複雑になるからである。

　俳諧(はいかい)では単に「三寒」とも「四温」ともいい、「四温日和(びより)」とともに冬の季語。

［根本順吉］

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