When we write out the date in a sentence, sometimes we must use two commas. There must be a comma after the day of the month and the even after the year. This is only when the sentence continues after the date with additional information.
Example 1 - March 28, 2009, was the date of the spring festival.
Example 2 -I will do the chores June 15, 2016, so that I can share in the workload.