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.
Leap years that begin on Monday, along with those starting on Saturday and Thursday, occur least frequently: 13 out of 97 (≈ 13.402%) total leap years in a 400-year cycle of the Gregorian calendar. Their overall occurrence is thus 3.25% (13 out of 400).
| 16th century | prior to first adoption (proleptic) | 1596 | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 17th century | 1624 | 1652 | 1680 | ||||||||
| 18th century | |||||||||||
| 19th century | |||||||||||
| 20th century | 1996 | ||||||||||
| 21st century | |||||||||||
| 22nd century | |||||||||||
| 23rd century | |||||||||||
| 24th century | 2396 | ||||||||||
| 25th century | |||||||||||
| 26th century | 2520 | 2548 | 2576 | ||||||||
| 27th century | 2616 | 2644 | 2672 | ||||||||
| 0–99 | 24 | 52 | 80 | ||
|---|---|---|---|---|---|
| 100–199 | 120 | 148 | 176 | ||
| 200–299 | 216 | 244 | 272 | ||
| 300–399 | 312 | 340 | 368 | 396 |
Like all leap year types, the one starting with 1 January on a Monday 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 position in the cycle is given by the formula ((year + 8) mod 28) + 1).
| 14th century | 1392 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 15th century | |||||||||||
| 16th century | |||||||||||
| 17th century | 1700 | ||||||||||
| 18th century | |||||||||||
| 19th century | 1896 | ||||||||||
| 20th century | 1924 | 1952 | 1980 | ||||||||
| 21st century | 2008 | 2036 | 2064 | 2092 | |||||||
| 22nd century | 2120 | 2148 | 2176 |