CORRESPONDING MONTHS

September and December always start on the same day of the week as each other.

The term "corresponding months" refers to months that begin on the same day of the week within a particular year. The only corresponding months in both common years and leap years are September and December. During common years, January and October; February, March and November; and April and July also correspond. In a leap year, January, April and July; March and November; and February and August are corresponding months.