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The 24 Solar Terms: A Complete Overview

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What are the 24 solar terms?

The 24 solar terms divide the sun's position along the ecliptic into 24 equal segments of 15 degrees each, based on the sun's movement rather than the moon. Because of this, each term's date on the solar (Gregorian) calendar stays nearly fixed from year to year, typically shifting by only a day or two.

The spring terms -- from Beginning of Spring to Grain Rain

Beginning of Spring (around February 4), Rain Water, Awakening of Insects, Spring Equinox (around March 21), Pure Brightness, and Grain Rain mark the start of spring and the traditional lead-up to planting season.

The summer terms -- from Beginning of Summer to Greater Heat

Beginning of Summer (around May 5), Grain Full, Grain in Ear, Summer Solstice (around June 21, the longest day of the year), Minor Heat, and Greater Heat mark the height of the growing and hot season.

The autumn terms -- from Beginning of Autumn to Frost's Descent

Beginning of Autumn (around August 7), End of Heat, White Dew, Autumn Equinox (around September 23), Cold Dew, and Frost's Descent mark the retreat of summer heat and the traditional harvest period.

The winter terms -- from Beginning of Winter to Greater Cold

Beginning of Winter (around November 7), Minor Snow, Major Snow, Winter Solstice (around December 22, the longest night of the year), Minor Cold, and Greater Cold mark the coldest stretch of the year.

The two equinoxes and two solstices

The Spring Equinox, Summer Solstice, Autumn Equinox, and Winter Solstice are the four terms marking either equal day and night length, or the longest day or night of the year -- widely considered the most significant reference points among all 24 terms.

The four "beginning" terms

Beginning of Spring, Beginning of Summer, Beginning of Autumn, and Beginning of Winter each mark the traditional start of a new season, serving as the turning points between them.

How solar terms differ from lunar holidays

Solar terms are a season-marking system based on the sun's position, while holidays like Lunar New Year or the Mid-Autumn Festival are set by the lunar calendar. A few terms, like the Winter Solstice, also carry their own folk customs, but the two systems are generally distinct.

A solar system often mistaken for a lunar one

The 24 solar terms are frequently discussed alongside the lunar calendar, but they are actually based entirely on the sun's position, not the moon's phases. That is exactly why, unlike lunar holidays, a given solar term's date on the Gregorian calendar stays nearly fixed year to year.

A shared system across East Asia, with local variation

The 24 solar terms originated in ancient China and have long been used across China, Korea, Japan, Vietnam, and other parts of East Asia as a shared solar-based timekeeping system, and in 2016 UNESCO recognized this knowledge system as part of humanity's Intangible Cultural Heritage. That said, the folk customs and foods associated with each term have developed somewhat differently in each country.

Frequently Asked Questions

Are the 24 solar terms used only in one country?

No -- the system originated in ancient China and has long been shared across China, Korea, Japan, Vietnam, and other East Asian countries, though the specific customs tied to each term developed somewhat differently in each place.

Why does a term's date shift by a day or two each year?

Earth's orbit around the sun is an ellipse rather than a perfect circle, and a year is not an exact whole number of days (about 365.24), so the exact moment the sun reaches a given position on the ecliptic drifts slightly year to year -- which is why solar term dates typically vary by about a day or two.