13th night of the lunar month; moon-viewing on the 13th night of the 9th lunar month
Refers to the 13th day of a lunar month, especially the traditional moon-viewing custom on the 13th night of the 9th lunar month (around October). Often paired with 十五夜 (the 15th-night moon-viewing).
This year's 13th-night moon-viewing was cloudy and we couldn't see the moon.
It is said to be auspicious to do moon-viewing on both the 15th night and the 13th night.
23rd night of a lunar month · moon-waiting party on the 23rd night
Compound of 十三 (thirteen) and 夜 (night), referring to the 13th night of the lunar month. The custom of moon-viewing on this night originated in Japan during the Heian period.