Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
January 06 Epiphany
April 01 Easter Monday
April 25 Liberation Day
May 01 International Workers' day
June 02 Republic Day
August 15 Assumption
November 01 All Saints
December 08 Imaculate Conception
December 25 Christmas
December 26 St Stephen's Day
DateTimeExtensions DateTimeExtensions