September 20 Holidays, events and History 2021.
| Date | Day | Holiday Name | Holiday Type | Country |
| 20 Sep | Monday | Respect for the Aged Day | National holiday | Japan |
| Sep 20 | Monday | Harvest Festival Holiday | National Holiday | South Korea |
| 20 Sep | Monday | Binara Full Moon Poya Day | Public Holiday | Sri Lanka |
| 20 Sep | Monday | Federal Fast Monday | Common local holiday | Switzerland |