Tirgan (Persian: تیرگان, Tirgān), is an early summer ancient Iranian festival, celebrated annually on Tir 13 (July 2, 3, or 4).

It is celebrated by splashing water, dancing, reciting poetry, and serving traditional foods such as spinach soup and sholezard.

The custom of tying rainbow-colored bands on wrists, which are worn for ten days and then thrown into a stream, is also a way to rejoice for children.

It is stated in Biruni's chronology that "by the order of God, the wind bore the arrow away from the mountains of Amol and brought the utmost frontier of Khorasan between Fergana and Tapuria.

Tirgan is celebrated every year in Mazandaran Province and Amol in northern Iran, the capital Tehran, Karaj, and the central and southern cities of Yazd, Meybod, Ardakan, Kerman, Bam, Shiraz, Isfahan, Ahvaz, and Farahan.