- Period
- Transition
- Solar longitude
24 Solar Terms Finder
Find the 24 solar term for a date, with its transition time, seasonal notes, and the corresponding 72 kō reference.
Your input is not sent to a server. All processing is performed locally in your browser.
Find a solar term by date
Dates are evaluated as calendar dates in Japan Standard Time (JST).
Current 72 kō
Reference period:
The 72 kō period shown here is a reference calculated by dividing the Sun’s apparent ecliptic longitude into 5° intervals. Names and dates may vary by calendar and source.
About this period
Seasonal characteristics
Seasonal foods
Plants & nature
Events & customs
| Solar term | Start date | Transition time (JST) |
|---|
Calculated from the Sun’s apparent ecliptic longitude with Astronomy Engine and evaluated by JST calendar date.
What are the 24 solar terms?
The 24 solar terms divide the Sun’s apparent ecliptic longitude into 24 segments of 15 degrees. Terms such as the equinoxes, solstices, Risshun, and Hakuro have long served as seasonal markers for farming and annual customs.
How to use this tool
- Enter the date you want to check in Japan Standard Time (JST).
- Select Search to see the solar term, exact transition time, and a reference 72 kō period for that calendar date.
- Use the previous and next day buttons or browse all 24 transitions for the selected year.
Why dates change from year to year
Earth’s orbital period does not align perfectly with a calendar year. Because each transition is calculated from the Sun’s apparent longitude rather than a fixed date, its date and time can shift slightly each year. Traditional term names also do not guarantee matching modern weather or temperature.
JST calendar-date rule
This is a date finder rather than a time finder. The entire JST date on which a transition occurs is treated as the new solar term. Even when the astronomical transition happens late at night, the result changes from the beginning of that calendar date and shows the exact transition time separately.
About the 72 kō
The 72 kō divide each solar term into three smaller seasonal passages described by brief observations of nature. This tool divides apparent solar longitude into 5-degree intervals and shows the corresponding name, reading, phase, and reference period.
The 72 kō dates are a reference
Modern Japanese calendars do not assign a single official transition time to all 72 kō, and different calendars and sources may use different names or dates. Treat the 5-degree periods shown here as a seasonal reference.
FAQ
What are the 24 solar terms?
They are 24 seasonal divisions defined at 15-degree intervals of the Sun’s apparent ecliptic longitude, changing about every 15 days.
Do Risshun and the equinoxes occur on the same date every year?
No. Their dates and transition times can shift slightly because they are calculated from the Sun’s apparent longitude.
Why does the new term apply before its exact transition time?
This tool searches by calendar date. It assigns the new term to the whole JST date on which the transition occurs and lists the exact astronomical time separately.
Are the dates of all 72 kō officially fixed?
No single set of 72 modern official transition times is used here. The reference periods are calculated by dividing apparent solar longitude into 5-degree intervals.
Will I get the same result outside Japan?
Yes. The input date and every transition are evaluated using Japan Standard Time (JST) as a fixed UTC+9 offset, regardless of your device time zone.
Is my date sent anywhere for calculation?
No. Astronomy Engine performs all calculations locally in your browser.