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
April 19 Good Friday
April 21 Easter
April 22 Easter Monday
April 25 Anzac Day
June 03 Queen's Birthday
October 28 Labour Day
December 25 Christmas
December 26 Boxing Day
DateTimeExtensions DateTimeExtensions