From Mar 30, 2026 to Apr 4, 2026, the corresponding solar term in the Nijūshi Sekki (24 solar terms) is 春分(Shunbun), and the corresponding microseason in the Shichijūni Kō (72 microseasons) is 雷乃発声(Kaminari sunawachi koe wo hassu).

What Is “Kaminari sunawachi koe wo hassu” (雷乃発声)?

"Kaminari Sunawachi Koe wo Hassu" (雷乃発声, "Thunder Begins to Resound") is one of the traditional Japanese seasonal markers known as the Shichijūni Kō (72 microseasons). It usually falls between March 31 and April 4 each year. The Shichijūni Kō is a traditional calendar system that divides the year into 72 finely detailed seasonal phases, expressing subtle changes in nature throughout the year. Since ancient times, it has served as a guide for agriculture and daily life. "Kaminari Sunawachi Koe wo Hassu" is one of the spring microseasons and refers to "the time when thunder, having slept quietly through the winter, awakens and rumbles across the spring sky for the first time." The expression originated from the Chinese calendar tradition and has long been passed down in Japan as well. This period marks a major seasonal transition from winter to spring. As temperatures begin to rise and the atmosphere becomes more unstable, a distinctive type of thunder known as Shunrai (春雷, "spring thunder") becomes more common. Unlike the intense thunderstorms of summer, spring thunder is often relatively mild and short-lived. For people in earlier times, it was welcomed as "the sound announcing the arrival of spring." In the world of haiku, Shunrai is also used as a seasonal word associated with spring, reflecting how the Japanese have long sensed the breath of the seasons through the sounds of nature. There is also a traditional belief in many regions of Japan that "when thunder rolls, it foretells a good harvest," showing the deep connection between this expression and Japan's agricultural culture. Even today, when we hear the sound of spring thunder during the season of "Kaminari Sunawachi Koe wo Hassu," it can be felt as more than a simple change in the weather. It is also a moment in which Japan's rich appreciation of nature and the wisdom of past generations continue to live on. By learning about the Shichijūni Kō, we can discover the joy of noticing the subtle transitions of the seasons in our everyday lives.

List of Japan’s 72 Microseasons