From the Japan Meteorological Agency. The table below is from the National Astronomical Observatory of Japan.
| Name | In Japanese | Meaning | Date (2026) | Time | Sun’s longitude |
|---|---|---|---|---|---|
| Shokan | 小寒 | Small cold | Jan 5 | 17:23 | 285° |
| Daikan | 大寒 | Great cold | Jan 20 | 10:45 | 300° |
| Risshun | 立春 | Start of spring | Feb 4 | 5:02 | 315° |
| Usui | 雨水 | Rain water | Feb 19 | 0:52 | 330° |
| Keichitsu | 啓蟄 | Insects wake up | Mar 5 | 22:59 | 345° |
| Shunbun | 春分 | Spring equinox | Mar 20 | 23:46 | 0° |
| Seimei | 清明 | Clear and bright | Apr 5 | 3:40 | 15° |
| Kokuu | 穀雨 | Grain rain | Apr 20 | 10:39 | 30° |
| Rikka | 立夏 | Start of summer | May 5 | 20:49 | 45° |
| Shoman | 小満 | Small fullness | May 21 | 9:37 | 60° |
| Boshu | 芒種 | Grain in ear | Jun 6 | 0:48 | 75° |
| Geshi | 夏至 | Summer solstice | Jun 21 | 17:25 | 90° |
| Shosho | 小暑 | Small heat | Jul 7 | 10:57 | 105° |
| Taisho | 大暑 | Great heat | Jul 23 | 4:13 | 120° |
| Risshu | 立秋 | Start of autumn | Aug 7 | 20:43 | 135° |
| Shosho | 処暑 | End of the heat | Aug 23 | 11:19 | 150° |
| Hakuro | 白露 | White dew | Sep 7 | 23:41 | 165° |
| Shubun | 秋分 | Autumn equinox | Sep 23 | 9:05 | 180° |
| Kanro | 寒露 | Cold dew | Oct 8 | 15:29 | 195° |
| Soko | 霜降 | Frost falls | Oct 23 | 18:38 | 210° |
| Ritto | 立冬 | Start of winter | Nov 7 | 18:52 | 225° |
| Shosetsu | 小雪 | Small snow | Nov 22 | 16:23 | 240° |
| Taisetsu | 大雪 | Great snow | Dec 7 | 11:53 | 255° |
| Toji | 冬至 | Winter solstice | Dec 22 | 5:50 | 270° |
The Japan Meteorological Agency keeps a list of the words it uses in forecasts. In that list, spring is the period from March to May, summer from June to August, autumn from September to November, and winter from December to February.
The same list has two longer periods for long-range forecasts: the warm season, from April to September, and the cold season, from October to March.
It also has a word for the height of summer, seika. It means roughly the time from the end of the rainy season to the end of August. In Hokkaido it means roughly July and August.
Seasons change because the Earth goes around the Sun with its axis tilted by about 23.4 degrees. So the Earth’s place on its path tells us the season.
The solstices and equinoxes are the best-known markers. The 24 solar terms (nijushi-sekki) divide the path more finely into 24 markers. Each one is set by the Sun’s position, called its longitude, in steps of 15 degrees.
In the solar calendar we use today, each solar term falls on almost the same date every year. The National Astronomical Observatory of Japan works out the exact moments each year; the table above shows them for 2026.
The 24 solar terms were added to UNESCO’s list of Intangible Cultural Heritage in 2016.
Risshun, the start of spring, comes halfway between the winter solstice and the spring equinox. In the same way, the starts of summer, autumn and winter each come halfway between a solstice and an equinox.
In the calendar, spring begins at Risshun. Seasonal greeting cards change on that day: cards for the cold season become cards for the “remaining cold.” In the same way, after Risshu, the start of autumn, summer greeting cards become cards for the “remaining heat.”
Risshun comes right after the two coldest terms, Shokan and Daikan, so it is natural that cold days go on after it.
The solar terms began as an idea in ancient northern China, so their names do not always fit the climate of Japan today.
The calendar also has other seasonal days. In 2026, Setsubun is on February 3, the day before Risshun.
In 2026, Hachiju-hachiya (“the 88th night”) is on May 2, Nyubai (“entering the rainy season”) is on June 11, and Nihyaku-toka (“the 210th day”) is on September 1.
Higan, a time around each equinox, begins on March 17 and on September 20 in 2026. The middle day of each higan is the equinox day.
There is no single right answer. Talking it over with someone at home is a good way to learn.