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 29 Good Friday
March 31 Easter
April 01 Easter Monday
April 25 Anzac Day
June 03 Queen's Birthday
October 28 Labour Day
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions