Long before clocks or satellites, Chinese farmers needed a way to know exactly when to plough, plant, irrigate and harvest. The lunar calendar told them what month it was, but months defined by the moon do not track the sun's annual journey with enough precision for agriculture. So around 2,500 years ago, Chinese astronomers created a parallel system: 24 markers spaced roughly 15 days apart through the solar year, each one signalling a specific shift in weather, daylight or natural activity.
These are the 24 Solar Terms (Ershisi Jieqi, δΊεεθζ°), and they are still in active use. In 2016, UNESCO inscribed them as an Intangible Cultural Heritage of Humanity, recognising a system that has guided agricultural and cultural life across East Asia for over two millennia.
How the System Works
The 24 Solar Terms divide the sun's annual path (the ecliptic) into 24 equal segments of 15 degrees each. Each time the sun crosses one of these positions, a new term begins. Because the terms track the sun's actual position rather than the moon's phases, they fall on nearly the same Gregorian dates each year, varying by only a day or two.
The terms alternate between "major" (Zhongqi) and "minor" (Jieqi) terms, though in practice both are treated as equally significant markers. They begin with the Start of Spring (Lichun) in early February and cycle through the full year, capturing the progression from winter dormancy through spring growth, summer heat, autumn harvest and winter return.
This solar framework sits alongside the lunar month system in the Chinese calendar. The combination is what makes the Chinese calendar lunisolar rather than purely lunar: months follow the moon, but the solar terms anchor the calendar to the agricultural seasons.
Spring (February through April)
Lichun - Start of Spring (Feb 3-5)
The first term of the year marks the astronomical beginning of spring. In northern China, the ground is still frozen, but the day length is increasing noticeably. Traditionally this was the day to begin planning the agricultural year. Many families eat spring rolls (chunjuan) to mark the occasion, and in some regions farmers ceremonially break the first soil.
Yushui - Rain Water (Feb 18-20)
Snow transitions to rain. Temperatures begin rising above freezing consistently, and the first rains soften the soil for spring ploughing. Wild geese begin their northward migration. Fishermen in southern China note this as the beginning of the freshwater spawning season.
Jingzhe - Awakening of Insects (Mar 5-7)
Hibernating creatures stir. The name literally means "startled insects" and tradition holds that the first spring thunder wakes them. Farmers watch for the emergence of earthworms and ground beetles as a signal that the soil is warming enough to work. Peach blossoms begin opening in central China.
Chunfen - Spring Equinox (Mar 20-22)
Day and night are equal. The sun crosses the celestial equator heading north. This is one of the four terms that correspond to astronomical events recognised worldwide. Rice paddies in southern China are prepared for flooding, and the first tea harvests begin in Fujian and Zhejiang provinces.
Qingming - Clear and Bright (Apr 4-6)
Perhaps the most culturally significant term. Qingming is both a solar term and a major festival. Families visit ancestral graves, clean the sites and make offerings. It is also the traditional marker for planting: willows are green, temperatures are consistently mild and rainfall is reliable. The phrase "Qingming planting melons and beans" is one of the most widely known agricultural proverbs in Chinese.
Guyu - Grain Rain (Apr 19-21)
The last spring term. Rainfall intensifies, providing the moisture needed for grain crops. The name refers specifically to the rain that "nourishes the hundred grains." Tea picked before Guyu (Mingqian tea) is prized as the highest quality of the year because the leaves are tender and have been growing slowly through cool spring weather.
Summer (May through July)
Lixia - Start of Summer (May 5-7)
Summer begins. In the Yangtze River valley, temperatures regularly exceed 22 degrees Celsius. Farmers watch the fullness of grain ears to judge crop progress. Traditionally people weigh themselves on this day, believing summer heat will cause weight loss and comparing again at the Start of Autumn to check.
Xiaoman - Grain Buds (May 20-22)
Grain crops are filling but not yet ripe. The name means "small full" referring to the grain kernels that are plumping but not complete. Silkworms begin spinning cocoons. In southern China, the plum rains (meiyu) season approaches, bringing weeks of continuous damp weather.
Mangzhong - Grain in Ear (Jun 5-7)
Bearded grains like wheat and barley are ready for harvest while rice seedlings must be transplanted into paddies. This is one of the busiest periods in the agricultural calendar: farmers are simultaneously harvesting one crop and planting another. The Chinese saying goes "Mangzhong is busy planting" and historically the entire family worked dawn to dusk during this term.
Xiazhi - Summer Solstice (Jun 21-22)
The longest day of the year. The sun reaches its highest point in the northern sky. Despite the maximum daylight, the hottest weather is still ahead because the ground has not yet absorbed enough heat. Noodles are traditionally eaten on this day in northern China, and some regions measure the shadow of a vertical pole at noon as a traditional astronomical observation.
Xiaoshu - Minor Heat (Jul 6-8)
Heat intensifies. The hottest period of the year (the "Three Fu Days") typically begins during this term. Fireflies appear in rural areas, which traditional observers used as a biological confirmation that the heat peak was approaching. Lotus flowers bloom in ponds across central and southern China.
Dashu - Major Heat (Jul 22-24)
The hottest term of the year. Temperatures in inland China routinely exceed 35 degrees Celsius. This is paradoxically also one of the wettest periods, with heavy afternoon thunderstorms common. Farmers irrigate intensively and watch for drought stress in rice paddies. Drinking herbal tea and eating chilled foods are traditional ways to manage the heat.
Autumn (August through October)
Liqiu - Start of Autumn (Aug 7-9)
Autumn begins, though summer heat typically continues for several weeks. The term signals a shift in agricultural priorities toward ripening and harvest preparation. Traditionally families "paste autumn fat" by eating rich foods to build reserves for winter. Morning dew becomes heavier as overnight temperatures begin their gradual decline.
Chushu - End of Heat (Aug 22-24)
The summer heat finally breaks. Night temperatures drop noticeably and the temperature range between day and night widens. Cotton bolls begin opening in the northern plains. Hawks and eagles become more active in the cooling air, and traditional observers considered their hunting behaviour a reliable sign that autumn had truly arrived.
Bailu - White Dew (Sep 7-9)
Morning dew is heavy enough to be visible on grass and leaves, appearing white in the early light. The name is poetic but observationally precise. Migratory birds begin moving south. Grapes ripen, and in wine-producing regions of Ningxia and Xinjiang, the harvest approaches. The famous Chinese poem by Du Fu references Bailu as a marker of autumn melancholy.
Qiufen - Autumn Equinox (Sep 22-24)
Day and night are equal again. The sun crosses the celestial equator heading south. Rice harvest begins across the central and southern regions. Osmanthus flowers bloom, filling the air with their distinctive fragrance, and osmanthus wine and cakes are traditional seasonal foods.
Hanlu - Cold Dew (Oct 8-9)
Dew becomes cold to the touch. Frost is imminent in northern regions. The chrysanthemum blooms and chrysanthemum tea is drunk. Farmers complete the harvest of late-season crops and begin preparing fields for winter. The observation "Hanlu, Hanlu, everywhere harvest" captures the urgency of this period.
Shuangjian - Frost Descent (Oct 23-24)
The first frost arrives in the northern plains and highlands. Maple leaves turn red in mountainous areas, drawing visitors to famous viewing spots. The last of the autumn harvest is completed, and root vegetables like turnips and radishes are stored for winter. Traditional medicine considers this an important time to nourish the lungs and respiratory system against the coming cold.
Winter (November through January)
Lidong - Start of Winter (Nov 7-8)
Winter begins. In northern China, rivers begin freezing and the first snow falls in higher elevations. Families prepare winter stores: pickling vegetables (particularly Chinese cabbage), drying meats and stocking fuel. Eating dumplings on Lidong is widespread in northern China, tracing to a tradition attributed to the physician Zhang Zhongjing who prescribed hot dumplings to prevent frostbitten ears.
Xiaoxue - Minor Snow (Nov 22-23)
Light snow falls in northern regions, though accumulation is minimal. Temperatures drop below freezing consistently. Farmers slaughter livestock for winter meat and begin the process of curing and smoking. The ground hardens, making fieldwork impossible in most of the north.
Daxue - Major Snow (Dec 6-8)
Heavy snowfall blankets northern China. Rivers and lakes freeze thick enough for crossing. Agricultural activity effectively pauses until spring. Families focus on indoor work: repairing tools, weaving, and preparing materials for the new year. Ice fishing begins on frozen lakes in Heilongjiang and Inner Mongolia.
Dongzhi - Winter Solstice (Dec 21-23)
The shortest day of the year and one of the most culturally important terms. Dongzhi is celebrated almost like a festival: families in southern China eat tangyuan (glutinous rice balls) while northern families eat dumplings. Historically Dongzhi marked the beginning of the "counting of the nines" (Shu Jiu), nine periods of nine days each until spring returns. The solstice was also a day for ancestral worship and family gatherings.
Xiaohan - Minor Cold (Jan 5-7)
Despite the name, Xiaohan is often the coldest period of the year in many parts of China, colder even than Major Cold. The "Third Nine" period of the counting falls here, traditionally considered the bitterest cold. Outdoor activity is minimal. Families prepare for the approaching Lunar New Year, cleaning homes and beginning to shop for festival supplies.
Dahan - Major Cold (Jan 20-21)
The final term of the year. The last deep cold before the cycle begins again with the Start of Spring. Preparations for Lunar New Year intensify. Markets sell spring couplets, paper decorations and festival foods. The year's agricultural narrative draws to a close, and farmers begin planning for the new cycle that starts with Lichun.
Why They Still Matter
Modern weather forecasting has made the predictive function of the solar terms less essential, but their cultural role has if anything expanded. Food culture across China and East Asia remains deeply tied to the terms: specific dishes are associated with specific markers, seasonal ingredients are valued precisely because they align with a term, and traditional medicine prescribes dietary adjustments keyed to the solar calendar.
The 24 Solar Terms also represent something conceptually powerful: the idea that time is not just measured but experienced through the natural world. Each term is named for something observable - rain, insects, dew, frost, grain, heat. The system assumes that a calendar should tell you not just what day it is but what the world around you is doing. In an era of climate-controlled buildings and year-round imported food, that assumption carries a different kind of value than it did two thousand years ago, but it has not stopped carrying value.