The United Nations observes the International Day of Nowruz on March 21.
The UN General Assembly established the observance through Resolution 64/253, adopted in February 2010. The date reflects Nowruz’s close association with the vernal equinox and the beginning of spring in the Northern Hemisphere.
Nowruz means “new day” in Persian and marks the new year in Iranian and related calendars. Although the astronomical equinox can occur on March 20 or March 21 depending on the year and time zone, the UN’s official international observance is fixed on March 21.
A common mix-up is confusing the UN observance with the precise calendar date of the festival itself. In Iran and other countries, Nowruz begins at the exact moment of the equinox, so its local date may vary. The UN date is an institutional observance, not a claim that every celebration begins on the same Gregorian date.