24 Solar Terms Complete Guide

What Are the 24 Solar Terms?

The 24 solar terms (二十四节气, èrshísì jiéqì) are a traditional Chinese calendar system that divides the solar year into 24 equal periods, each approximately 15 days long. Each term marks a specific point in the sun's apparent motion along the ecliptic — the path the sun traces across the sky as seen from Earth. By observing these astronomical markers, ancient Chinese farmers knew exactly when to plow, sow, irrigate, and harvest.

Unlike the purely lunar calendar, which follows the moon's phases, the solar terms are tied to the sun and therefore correspond consistently to the Gregorian calendar dates — shifting by only a day or two each year. This makes them an extraordinarily reliable guide to the changing seasons. A farmer in the Yellow River valley 3,000 years ago and a modern meteorologist today can agree on the same seasonal rhythm: when 立春 (Lìchūn, Spring Begins) arrives in early February, the worst of winter is over, regardless of what the lunar calendar might say.

"When heaven and earth revolve, the four seasons follow one another. The sun and moon alternate, each shining in its turn. Thus the sage follows the seasons and does not force action against the times."

— The Book of Changes (I Ching), Appended Judgments (trans. Richard Wilhelm)

The Chinese term 节气 (jiéqì) literally means "seasonal node" or "seasonal breath." Each term was named after a natural phenomenon — the first thunder of spring, the appearance of dewdrops, the descent of frost. These names are themselves a window into how ancient Chinese civilization understood and poetically described the rhythms of the natural world.

Origin and History

The 24 solar terms evolved over centuries of astronomical observation in the Yellow River basin (黄河流域), the cradle of Chinese civilization. The climate of this region — cold dry winters, hot rainy summers, and two transitional periods of mild weather — shaped the system's emphasis on precise seasonal timing for agriculture.

"The sage follows the changes of the seasons and adapts to the transformations of things. He does not impose his will upon the natural world but moves in harmony with its rhythms."

— Huainanzi, Chapter 1, Originating in the Way (trans. John S. Major)

The earliest evidence of seasonal division in China dates to the Shang dynasty (商朝, ~1600–1046 BCE). Oracle bone inscriptions record observations of the solstices and equinoxes — the four cardinal points of the solar year. By the Zhou dynasty (周朝, ~1046–256 BCE), Chinese astronomers had identified eight key seasonal nodes: the two solstices, two equinoxes, and the four "beginnings" of each season.

The full system of 24 terms was formalized during the Western Han dynasty (西汉, 206 BCE – 9 CE). The text Huainanzi (淮南子), compiled in 139 BCE under the patronage of Prince Liu An, contains the first complete list of all 24 solar terms with their names and positions — essentially the same names used today. This was a remarkable achievement of ancient astronomy, accomplished without telescopes or modern instruments.

Over subsequent dynasties, the accuracy of the solar term calculations improved dramatically. During the Yuan dynasty (元朝, 1271–1368), the astronomer Guo Shoujing (郭守敬) created the Shoushi Calendar (授时历), which calculated the tropical year to 365.2425 days — a precision not achieved in Europe until the Gregorian calendar over three centuries later. The Ming dynasty's Datong Calendar and the Qing dynasty's Shixian Calendar (based on Jesuit astronomical methods) further refined the system.

How the Solar Terms Are Calculated

The 24 solar terms are based on a purely astronomical principle: the division of the sun's apparent annual path — the ecliptic — into 24 equal segments of 15° of solar longitude each.

The 0° reference point is the Spring Equinox (春分, Chūnfēn), when the sun crosses the celestial equator moving north. From there, every 15° of additional solar longitude marks the beginning of the next solar term:

• 0° — Spring Equinox (春分, Chūnfēn)
• 15° — Pure Brightness (清明, Qīngmíng)
• 30° — Grain Rain (谷雨, Gǔyǔ)
• 45° — Summer Begins (立夏, Lìxià)
• ... and so on through all 24 terms, up to 345° — the last term before returning to 0°.

Each solar term spans approximately 15.2 days (since 360° ÷ 24 = 15°, and 365.24 days ÷ 24 ≈ 15.2 days). The terms are divided into two categories:

• 节气 (jiéqì) — "Major Solar Terms": 12 terms that begin with jié (node), including the solstices, equinoxes, and the four season beginnings. In some historical systems, these were the primary markers.
• 中气 (zhōngqì) — "Minor Solar Terms": 12 terms that fall in between the major ones. In the traditional lunisolar calendar, a month without a 中气 became an intercalary (leap) month.

Today, the exact timing of each solar term is calculated by the Purple Mountain Observatory (中国科学院紫金山天文台) in Nanjing and published in the annual Chinese Astronomical Almanac. Modern algorithms account for the ellipticity of Earth's orbit (which makes terms in January slightly longer than those in July) and use the precise position of the sun relative to the mean vernal equinox.

The Four Seasons and Their Terms

The 24 solar terms are organized into four seasons of six terms each. Each season begins with a "start" term (立, lì), peaks at an extreme (至, zhì for solstices; 分, fēn for equinoxes; 暑, shǔ for heat; 寒, hán for cold), and ends with a transitional term.

Spring (春季, chūnjì) — 立春 to 谷雨

Spring opens with 立春 (Lìchūn, Spring Begins) in early February — the traditional start of the agricultural year. Over the next three months, the earth warms, rains increase, insects awaken from hibernation, and crops begin their growth cycle. 清明 (Qīngmíng, Pure Brightness) in early April is both a solar term and a major festival for honoring ancestors.

Summer (夏季, xiàjì) — 立夏 to 大暑

Summer begins in early May with 立夏 (Lìxià, Summer Begins). The season covers the period of fastest crop growth, the longest day of the year (夏至, Summer Solstice), and culminates in the most intense heat of the year (大暑, Major Heat). Summer is a season of abundance but also of flood and pestilence — the solar terms remind farmers to drain fields and store grain.

Autumn (秋季, qiūjì) — 立秋 to 霜降

Autumn begins in early August with 立秋 (Lìqiū, Autumn Begins). The heat subsides, dewdrops appear, and the autumn equinox brings equal day and night. The season ends with 霜降 (Shuāngjiàng, Frost Descent), when the first frost signals the end of the growing season and the urgent need to harvest before winter.

Winter (冬季, dōngjì) — 立冬 to 大寒

Winter begins in early November with 立冬 (Lìdōng, Winter Begins). As temperatures drop, snow appears, and the winter solstice (冬至, Dōngzhì) marks the shortest day and longest night of the year in the Northern Hemisphere. The coldest days come after the solstice, during 小寒 (Minor Cold) and 大寒 (Major Cold) in January, before the cycle begins again with 立春.

Complete Table of the 24 Solar Terms

UNESCO Intangible Cultural Heritage (2016)

On November 30, 2016, the United Nations Educational, Scientific and Cultural Organization (UNESCO) officially inscribed "The Twenty-Four Solar Terms, knowledge in China of time and practices developed through observation of the sun's annual motion" on its Representative List of the Intangible Cultural Heritage of Humanity.

The UNESCO citation recognized the solar terms as "knowledge of time and practices developed through observation of the sun's annual motion — encompassing the Chinese people's understanding of time, seasons, agriculture, and health." The inscription acknowledges not just the astronomical system itself, but the entire cultural ecosystem surrounding it: the folk songs, proverbs, seasonal foods, health practices, and festivals that have grown around each term over three millennia.

This recognition was a milestone for Chinese cultural heritage on the global stage. It placed the 24 solar terms alongside other UNESCO-listed Chinese traditions such as Peking opera (京剧), acupuncture (针灸), and the Dragon Boat Festival (端午节). The designation has spurred renewed interest in the solar terms within China itself, particularly among younger generations rediscovering their cultural heritage.

Solar Terms and Traditional Festivals

Several major Chinese festivals are directly tied to the solar terms:

Qingming Festival (清明节) — Pure Brightness

Falling on the 5th solar term (清明, around April 5), Qingming is one of the most important traditional festivals in the Chinese calendar. Families visit ancestral graves to sweep tombs, make offerings, and honor the deceased. The term's name — "Pure Brightness" — also reflects the clear weather and fresh green landscapes of early April, making it a traditional time for spring outings (踏青, tàqīng). Qingming is a public holiday in China, Taiwan, Hong Kong, and Macau.

Winter Solstice Festival (冬至) — Dongzhi

The 22nd solar term (冬至, around December 22) marks the winter solstice and is celebrated as a major festival throughout East Asia. In Chinese tradition, the winter solstice is a time for family reunion and the eating of tangyuan (汤圆, glutinous rice balls) in the south and dumplings (饺子, jiǎozi) in the north. The festival embodies the Taoist concept of yin and yang — the longest night of the year represents the peak of yin energy, after which yang begins its ascent as the days grow longer.

Spring Festival Connections

While the Lunar New Year (春节, Chūnjié) follows the lunisolar calendar, it always falls near 立春 (Lìchūn, Spring Begins) — the first solar term. The Chinese zodiac year is traditionally said to begin at 立春 rather than at the Lunar New Year, a distinction still observed by professional Chinese astrologers and calendar-makers.

Agricultural Observances

Each solar term has associated agricultural proverbs and practices. For example, 惊蛰 (Jīngzhé, Awakening of Insects) marks the time to begin spring plowing. 芒种 (Mángzhòng, Grain in Ear) signals the busy wheat harvest — its name literally means "busy planting" (芒种 sounds like 忙种). Farmers across rural China still follow these traditional timings, supplemented by modern meteorological forecasts.

Modern Relevance

The 24 solar terms are far from a historical curiosity. They remain actively used in contemporary China and across East Asia in several important ways:

Weather and Agriculture

Chinese weather services — from the national China Meteorological Administration to local apps — routinely display the current solar term alongside the standard date. Many farmers, especially older generations, continue to plan planting and harvest schedules around the solar terms. The terms are particularly valued as a long-range seasonal guide: they tell you not just today's weather but the expected pattern for the next two weeks.

Traditional Chinese Medicine (中医)

Traditional Chinese Medicine prescribes different health practices for each solar term. The system teaches that human physiology responds to the same seasonal energies that govern the natural world. For example, during 立春 (Spring Begins), the liver's energy is said to be most active, and TCM recommends lighter foods and gentler exercise. During 冬至 (Winter Solstice), the kidneys are emphasized, and warming, nourishing foods are encouraged. Seasonal health advice based on the solar terms is widely shared on Chinese social media platforms like WeChat and Weibo.

Education and Cultural Identity

Chinese schoolchildren learn the 24 solar terms as part of the national curriculum, often through a traditional mnemonic song (节气歌, jiéqì gē) that compresses all 24 names into a single, memorable rhyme. The solar terms also appear regularly in Chinese poetry, literature, and art — a living connection to the agrarian civilization that shaped Chinese identity over thousands of years.

The Solar Terms Song (节气歌)

春雨惊春清谷天，
夏满芒夏暑相连，
秋处露秋寒霜降，
冬雪雪冬小大寒。

This short rhyme encodes all 24 terms in just 28 characters. The first line covers spring (立春, 雨水, 惊蛰, 春分, 清明, 谷雨), the second covers summer (立夏, 小满, 芒种, 夏至, 小暑, 大暑), the third covers autumn (立秋, 处暑, 白露, 秋分, 寒露, 霜降), and the fourth covers winter (立冬, 小雪, 大雪, 冬至, 小寒, 大寒).

Global Recognition

Beyond China, the 24 solar terms are used in the traditional calendars of Japan (where they are called 二十四節気, nijūshi sekki), Korea (이십사절기, isipsa jeolgi), Vietnam (nhị thập tứ tiết), and other East Asian countries. Each culture adapted the system to its own climate and agricultural conditions, but the core astronomical framework remains the same.

Frequently Asked Questions

Oriens has mapped 71 philosophical concepts across 330 wisdom cards and 868 conceptual relationships

Sources & Further Reading

• Confucius. The Analects. Translated by D.C. Lau. Penguin Classics, 1979.
• Mencius. Mencius. Translated by D.C. Lau. Penguin Classics, 2004.
• Chan, Wing-tsit. A Source Book in Chinese Philosophy. Princeton University Press, 1963.

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