The short answer
The 24 solar terms divide the Sun’s annual apparent path into 15-degree steps. Their boundaries are astronomical instants; their names preserve seasonal cultural knowledge. Lunar months, festivals and local weather follow different rules, so these fields should be read separately.
Twenty-four positions around the solar year
Each modern solar term corresponds to a step of 15 degrees in the Sun’s apparent ecliptic longitude. The spring equinox is at 0 degrees, summer solstice at 90, autumn equinox at 180 and winter solstice at 270. Li Chun, Start of Spring, is at 315 degrees. These are astronomical markers, not dates chosen by the phase of the Moon.
Background: National Astronomical Observatory of Japan — 24 Solar Terms
Why the names are culturally meaningful
The names connect timekeeping with seasonal work and observations of nature. UNESCO recognizes the twenty-four solar terms as a body of cultural knowledge and practice. Preserving that meaning does not require treating every name as a literal description of every location’s weather on the boundary date.
Background: UNESCO — The Twenty-Four Solar Terms
Solar terms and lunar months do different jobs
Lunar months track the lunar cycle, while solar markers keep the calendar connected to the seasonal year. An inserted leap month can repeat a numbered month; it does not create an extra spring equinox or a second sequence of solar terms. The light calendar explicitly marks a leap month so that it is not confused with the ordinary month of the same number.
Background: Hong Kong Observatory — The Chinese Calendar
A date and an instant are not the same field
A solar term begins at a particular instant. That instant can fall on different civil dates in different timezones. Our calendar detects your browser timezone. Live Today follows your local date and the current instant, while choosing a date evaluates its current and next term at local noon. Term timestamps include the offset for that instant, so daylight saving time is respected. Lunar conversion still follows the traditional Chinese calendar for the displayed Gregorian date.
The transition time is computed and shown to the minute for learning. Near a boundary, compare an authoritative ephemeris if precision matters. Gregorian New Year, Lunar New Year and Start of Spring are separate events; replacing one with another changes the calendar or interpretive convention being used.
Festivals, seasons and local experience
Qingming is both the name of a solar term and a festival associated with its calendar date. Mid-Autumn Festival is instead tied to lunar month 8, day 15. A festival can therefore move through the Gregorian calendar for a different reason than a solar marker does.
For readers in the Southern Hemisphere, the astronomical marker still exists while the local season differs from the northern seasonal name. Treat the name as a cultural reference and observe the actual weather where you live. Neither the calendar nor the learning image supplies a local agricultural schedule or an auspicious-day rating.
| Marker | Solar longitude |
|---|---|
| Spring Equinox · Chunfen 春分 | 0° |
| Summer Solstice · Xiazhi 夏至 | 90° |
| Autumn Equinox · Qiufen 秋分 | 180° |
| Winter Solstice · Dongzhi 冬至 | 270° |
| Start of Spring · Lichun 立春 | 315° |
Start of Spring on February 4: why the hour matters
On the UTC+8 calendar, Start of Spring in 2026 falls on February 4. Before the computed transition instant, Major Cold remains the current solar term. After it, Start of Spring is current and Rain Water becomes next. The civil date can stay February 4 throughout that change. A calendar that displays only one name for the whole day must choose a convention, even when that convention is not explained.
House Quest makes the choice visible. Live Today follows the actual current instant, while a selected date uses noon in your browser timezone for its solar-term context. The listed transition times are calculated and displayed to the minute. Consequently, looking up February 4 as a selected date can show Start of Spring even if a live view earlier that morning still showed Major Cold. Compare reference instants before assuming that one of those views is wrong.
Now compare a lunar festival, such as Mid-Autumn Festival on month 8, day 15. Its Gregorian date changes through lunar-calendar conversion rather than by selecting the same solar longitude every year. An inserted leap month repeats a lunar month number, not the twenty-four-term sequence. Seeing these two examples side by side makes the lunisolar structure clearer than treating every seasonal or festival name as the same type of date.
A way to work through it
- Find the solar term’s transition instant and note the displayed timezone before comparing calendar dates.
- Distinguish Live Today from a picked date’s noon reference; compare equivalent instants when checking another source.
- Compare a solar term with a lunar festival, and keep local weather observations separate from both calendar rules.
Try an observation
Choose the day of a solar-term transition in the calendar, note its displayed timezone and local time, then compare the preceding and following days. Contrast that with the changing Gregorian date of Mid-Autumn Festival.
Common questions
Are solar terms based on the Moon?
Their modern boundaries are defined by the Sun’s apparent ecliptic longitude. Lunar months instead follow the lunar cycle. Both participate in the Chinese calendar, but the Moon’s phase does not choose the instant of an equinox, solstice or another solar-term boundary.
Are the 24 solar terms on the same dates every year?
They fall near recurring Gregorian dates, but their exact instants vary. A timezone can also change the civil date assigned to the same instant. Use the year’s calculated or published table when checking a boundary rather than treating a remembered date as universally exact.
What is Li Chun and is it Chinese New Year?
Li Chun means Start of Spring and corresponds to 315 degrees of solar longitude. Lunar New Year is the first day of the first civil lunar month. They are different events. The product displays both year conventions because an annual Feng Shui layer can use Li Chun.
Does Major Snow mean it will snow where I live?
The name preserves a northern seasonal vocabulary; it is not a local forecast. Climate, hemisphere and location affect actual weather. The astronomical marker remains meaningful worldwide, while the agricultural and cultural associations should be understood in the setting where they developed.
Sources & further reading
- National Astronomical Observatory of Japan — 24 Solar Terms
Astronomical definitions by apparent solar longitude. Names and regional customs differ.
- UNESCO — The Twenty-Four Solar Terms
Cultural heritage and seasonal knowledge, distinct from date-selection predictions.
- Hong Kong Observatory — The Chinese Calendar
The calendar combines lunar months with solar-year constraints.
Historical and traditional interpretations are distinguished from observable layout conditions. Worked examples are illustrative editorial scenarios, not documented client cases. Practical examples and product-scope explanations are editorial applications, not quoted source text. School conventions vary; these articles do not predict health, wealth or personal outcomes.