Add holidays to the calendar
When you first use Outlook 2013 or Outlook 2016 for Windows, there aren’t any holidays on the Calendar. But you can add holidays for one or more countries.
Click File > Options > Calendar.
Under Calendar options, click Add Holidays.
Check the box for each country whose holidays you want to add to your calendar, and then click OK.
If a country's or region's holidays are already added to your calendar, the box for the country is checked in the Add Holidays to Calendar dialog box. If you click OK, the holidays are added and duplicates are created.
Delete holidays and events
In Calendar, click View > Change View > List.
Select the holidays you want to delete. To select multiple rows, press the Ctrl key, and then click the Calendar icon to select more rows.
Click Home > Delete.
My holidays are missing
If you’ve been using Outlook for a few years, your calendar may be missing holidays for 2013 and beyond. Follow the steps above to add holidays.