Leap year starting on Friday
A leap year starting on Friday is any year with 366 days (i.e. it includes 29 February) that begins on Friday 1 January and ends on Saturday 31 December. Its dominical letters hence are CB. The most recent year of such kind was 2016 and the next one will be 2044 in the Gregorian calendar[1] or, likewise, 2000 and 2028 in the obsolete Julian calendar.
Any leap year that starts on Tuesday, Friday or Saturday has only one Friday the 13th: the only one in this leap year occurs in May. Common years starting on Saturday share this characteristic.
In this type of year, all dates (except 29 February) fall on their respective weekdays 58 times in the 400 year Gregorian calendar cycle. Leap years starting on Sunday share this characteristic.
Calendars
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| ISO 8601-conformant calendar with week numbers for any leap year starting on Friday (dominical letter CB) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Applicable years
Gregorian Calendar
Leap years that begin on Friday, along with those that start on Sunday, occur most frequently: 15 out of the 97 (≈ 15.46%) total leap years in a 400-year cycle of the Gregorian calendar. Thus, the overall occurrence is 3.75% (15 out of 400).
| Decade | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th | 10th |
|---|---|---|---|---|---|---|---|---|---|---|
| 17th century | 1616 | 1644 | 1672 | |||||||
| 18th century | 1712 | 1740 | 1768 | 1796 | ||||||
| 19th century | 1808 | 1836 | 1864 | 1892 | ||||||
| 20th century | 1904 | 1932 | 1960 | 1988 | ||||||
| 21st century | 2016 | 2044 | 2072 | |||||||
| 22nd century | 2112 | 2140 | 2168 | 2196 | ||||||
| 23rd century | 2208 | 2236 | 2264 | 2292 | ||||||
| 24th century | 2304 | 2332 | 2360 | 2388 | ||||||
| 25th century | 2416 | 2444 | 2472 | |||||||
| 26th century | 2512 | 2540 | 2568 | 2596 |
400 year cycle
century 1: 16, 44, 72
century 2: 112, 140, 168, 196
century 3: 208, 236, 264, 292
century 4: 304, 332, 360, 388
Julian Calendar
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 position in the cycle is given by the formula ((year + 8) mod 28) + 1).
| Decade | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th | 9th | 10th |
|---|---|---|---|---|---|---|---|---|---|---|
| 15th century | 1412 | 1440 | 1468 | 1496 | ||||||
| 16th century | 1524 | 1552 | 1580 | |||||||
| 17th century | 1608 | 1636 | 1664 | 1692 | ||||||
| 18th century | 1720 | 1748 | 1776 | |||||||
| 19th century | 1804 | 1832 | 1860 | 1888 | ||||||
| 20th century | 1916 | 1944 | 1972 | 2000 | ||||||
| 21st century | 2028 | 2056 | 2084 | |||||||
| 22nd century | 2112 | 2140 | 2168 | 2196 |
Wikimedia Commons has media related to Leap years starting on Friday and ending on Saturday.
Holidays
International
- Valentine's Day falls on a Sunday
- The leap day (February 29) falls on a Monday
- World Day for Grandparents and the Elderly falls on July 24
- Halloween falls on a Monday
- Christmas Day falls on a Sunday
Roman Catholic Solemnities
- Epiphany falls on a Wednesday
- Candlemas falls on a Tuesday
- Saint Joseph's Day falls on a Saturday
- The Annunciation of Jesus falls on a Friday
- The Nativity of John the Baptist falls on a Friday
- The Solemnity of Saints Peter and Paul falls on a Saturday
- The Transfiguration of Jesus falls on a Saturday
- The Assumption of Mary falls on a Monday
- The Exaltation of the Holy Cross falls on a Wednesday
- All Saints' Day falls on a Tuesday
- All Souls' Day falls on a Wednesday
- The Feast of Christ the King falls on its earliest possible date, November 20 (or on October 30 in versions of the calendar between 1925 and 1962)
- The First Sunday of Advent falls on its earliest possible date, November 27
- The Immaculate Conception falls on a Thursday
- Gaudete Sunday falls on its earliest possible date, December 11
- Rorate Sunday falls on its earliest possible date, December 18
Australia and New Zealand
- Australia Day falls on a Tuesday
- Waitangi Day falls on a Saturday
- Daylight saving ends on April 3
- ANZAC Day falls on a Monday
- Mother's Day falls on its earliest possible date, May 8
- Father's Day falls on September 4
- Daylight saving begins on September 25 in New Zealand and October 2 in Australia
British Isles
- Saint David's Day falls on a Tuesday
- Mother's Day falls on March 6, March 13, March 20, March 27 or April 3
- Daylight saving begins on March 27
- Saint Patrick's Day falls on a Thursday
- Saint George's Day falls on a Saturday
- Father's Day falls on June 19
- Orangeman's Day falls on a Tuesday
- Daylight saving ends on October 30
- Guy Fawkes Night falls on a Saturday
- Saint Andrew's Day falls on a Wednesday
Canada
- Daylight saving begins on March 13
- Mother's Day falls on its earliest possible date, May 8
- Victoria Day falls on May 23
- Father's Day falls on June 19
- Canada Day falls on a Friday
- Labour Day falls on September 5
- Thanksgiving Day falls on October 10
- Daylight saving ends on November 6
United States
- Martin Luther King Jr. Day falls on January 18
- President's Day falls on its earliest possible date, February 15
- Daylight saving begins on March 13
- Mother's Day falls on its earliest possible date, May 8
- Memorial Day falls on May 30
- Juneteenth and Father's Day coincide on Sunday, June 19
- Independence Day falls on a Monday
- Labor Day falls on September 5
- Grandparents' Day falls on September 11
- Columbus Day falls on October 10
- Daylight saving ends on November 6
- Election Day falls on its latest possible date, November 8
- Thanksgiving Day falls on November 24
References
- Robert van Gent (2017). "The Mathematics of the ISO 8601 Calendar". Utrecht University, Department of Mathematics. Retrieved 20 July 2017.
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