Chahārshanbe-Sūri meaning Wednesday Feast, from the word Sour which means party or feast and also red in Persian, is an ancient Persian festival dating at least to 1700 BCE of the early Zoroastrian era. The festival of fire is a prelude to the Nowruz festival, which marks the arrival of spring and revival of nature and at the same time start of new Iranian Year. Traditionally celebrated on the last Tuesday night of the year. The word Chahar Shanbeh means Wednesday and Suri is red. Bonfires are lit to keep the sun alive till early hours of the morning. The celebration usually starts in the evening, with people making bonfires in the streets and jumping over them.

The tradition includes people going into the streets and alleys to make fires, and jump over them while singing the song zardi-ye man az to, sorkhi-ye to az man. The literal translation is, my sickly yellow paleness is yours, your fiery red color is mine. This is a purification rite and 'soori' itself means redness which hints at the color of fire. Loosely translated, this means you want the fire to take your paleness, sickness, and problems and in turn give you redness, warmth, and energy. There is no religious significance attached to Chaharshanbeh Soori and it serves as a cultural festival for Persians, Persian Jews, Muslims, Armenians, Kurds, Turks and Zoroastrians alike. Indeed this celebration, in particular the significant role of fire, is likely to hail from Zoroastrianism.

Another tradition of this day is to make special ajeel, or mixed nuts and berries. People wear disguises and chadors and go door to door knocking on doors. Receiving of the Ajeel is customary, as is receiving of a bucket of water; however this tradition is weakened now a days.

In recent years, chaharshanbe suri has become a symbol of protest against government who tries to vanish this tradition by means of religious excuses.