Friday the 13th etc.) of the year. Any month that starts on a Sunday contains a Friday the 13th, and there is at least one Friday the 13th in every calendar year. There can be as many as three Friday the 13ths in a single calendar year; either in February, March and November in a common year starting on Thursday (such as 2009, 2015 or 2026) (D), or January, April and July in a leap year starting on Sunday (such as 2012) (AG). The longest period that occurs without a Friday the 13th is 14 months, either from July to September the following
Leap year starting on Friday share this characteristic. Leap years that begin on Friday, along with those that start on Sunday, occur most frequently: 15 out of the 97 (≈ 15.5%) total leap years in a 400-year cycle of the Gregorian calendar. Thus, the overall occurrence is thus 3.75% (15 out of 400). Like all leap year types, the one starting with 1 January on a Friday occurs exactly once in a 28-year cycle in the Julian calendar, i.e. in 3.57% of years. As the Julian calendar repeats after 28 years that means it will also repeat after 700 years, i.e. 25 cycles. The year's