Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 New Year
January 02 Day after New Year's Day
February 06 Waitangi Day
March 27 Good Friday
March 29 Easter
March 30 Easter Monday
April 25 Anzac Day
June 04 Queen's Birthday
October 22 Labour Day
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions