A traditional ancient Iranian festival celebrating the first day of Spring and the Iranian New Year. Also celebrated as New Year’s Day in Bahá’í tradition (Naw-Ruz). (This date may vary based on region or sect.)https://www.un.org/en/observances/international-nowruz-day  

Source:
“Calendar of Observances.” Anti-Defamation League, 2019, www.adl.org/education/resources/tools-and-strategies/calendar-of-observances. Accessed 25 Sept. 2020.