Examples
Christmas is December 25th.
Christmas is on December twenty-fifth.
Christmas Day is December 25th.
Source: Tatoeba
December is the last month of the year.
Source: Tatoeba
She died on a cold night in December.
Source: Tatoeba
She died on a cold night in December.
Source: Tatoeba
The Japanese attacked Pearl Harbor on December 7, 1941.
Source: Tatoeba
The Nobel Prize is awarded annually on December 10, the day of Alfred Nobel's death.
Source: Tatoeba