Just a sample site of a possible usage of DateTimeExtensions nuget package.
January 01 Ano Novo
March 07 Carnaval
April 21 Sexta-feira Santa
April 23 Pascoa
May 01 Dia do Trabalhador
June 22 Corpo de Cristo
September 07 Dia da Independência
October 12 Nossa Srª da Aparecida
November 02 Dia de Finados
November 15 Dia da Republica
December 25 Natal
DateTimeExtensions DateTimeExtensions