A leap year starting on Monday is any year with 366 days (i.e. it includes 29 February) that begins on Monday, 1 January, and ends on Tuesday, 31 December. Its dominical letters hence are GF. The current year, 2024, is a leap year starting on Monday in the Gregorian calendar. The last such year was 1996 and the next such year will be 2052 in the Gregorian calendar[1] or, likewise, 2008 and 2036 in the obsolete Julian calendar.
Any leap year that starts on Monday, Wednesday or Thursday has two Friday the 13ths: those two in this leap year occur in September and December. Common years starting on Tuesday share this characteristic.
Additionally, this type of year has three months (January, April, and July) beginning exactly on the first day of the week, in areas which Monday is considered the first day of the week, Common years starting on Friday share this characteristic on the months of February, March, and November.