Editing Leap year starting on Sunday

{{Short description|none}}
A '''leap year starting on Sunday''' is any year with 366 days (i.e. it includes 29 February) that begins on [[Sunday]], 1 January, and ends on [[Monday]], 31 December. Its [[dominical letter]]s hence are '''AG'''. The most recent year of such kind was [[2012]], and the next one will be [[2040]] in the [[Gregorian calendar]]<ref name="math">{{cite web|url=https://webspace.science.uu.nl/~gent0113/calendar/isocalendar.htm |author=Robert van Gent |title=The Mathematics of the ISO 8601 Calendar |publisher=Utrecht University, Department of Mathematics |date=2017 |access-date=20 July 2017}}</ref> or, likewise [[2024]] and 2052 in the obsolete [[Julian calendar]].

This is the only leap year with three occurrences of [[Friday the 13th]]: those three in this leap year occur three months (13 weeks) apart: [[January 13|in January]], [[April 13|April]], and [[July 13|July]]. [[Common year starting on Thursday|Common years starting on Thursday]] share this characteristic, in the months of February, March, and November.

Additionally, these types of years are the only ones which contain 54 different calendar weeks (2 partial, 52 in full) in areas of the world where Monday is considered the first day of the week.

This year has five months (January, April, July, September and December) which begin on a weekend-day. This is the greatest possible number of months to begin on a weekend-day in a given year; this is the only kind of year in which this occurs.

==Calendars==
<!-- To avoid arbitrary years, use the most recent year of this type. 2012 was the most recent year of this type. -->
{{calendar|year=2012|show_year=off|title=Calendar for any [[leap year]] starting on Sunday,<br />presented as common in many English-speaking areas}}

{{calendar|year=2012|show_year=off|format=iso|row=3|zero=0|title=[[ISO 8601]]-conformant calendar with [[ISO week date|week numbers]] for<br />any leap year starting on Sunday (dominical letter AG)}}

==Applicable years==
===Gregorian Calendar===
Leap years that begin on Sunday, along with those [[Leap year starting on Friday|starting on Friday]], occur most frequently: 15 of the 97 (≈ 15.46%) total leap years in a 400-year cycle of the [[Gregorian calendar]]. Thus, their overall occurrence is 3.75% (15 out of 400).

{| class="wikitable"
|+ Gregorian leap years starting on Sunday<ref name=math/>
!scope=row| Decade
! 1st !! 2nd !! 3rd !! 4th !! 5th !! 6th !! 7th !! 8th !! 9th !! 10th
|- style="opacity: 0.5;"

! style="background-color:#efefef;" | [[16th century]]
| colspan="8" | ''prior to first adoption (proleptic)''|| [[1584]]||
|-
![[17th century]]
|
|[[1612]]
|
|[[1640]]
|
|
|[[1668]]
|
|
|[[1696]]
|-
! style="background-color:#efefef;" | [[18th century]]
| [[1708]] || || || [[1736]] || || || [[1764]] || || || [[1792]]
|-
! style="background-color:#efefef;" | [[19th century]]
| [[1804]] || || || [[1832]] || || [[1860]] || || || [[1888]] || 
|-
! style="background-color:#efefef;" | [[20th century]]
| || || [[1928]] || || || [[1956]] || || || [[1984]] || 
|-
! style="background-color:#efefef;" | [[21st century]]
| || [[2012]] || || [[2040]] || || || [[2068]] || || || [[2096]]
|-
! style="background-color:#efefef;" | [[22nd century]]
| [[2108]] || || || [[2136]] || || || [[2164]] || || || [[2192]]
|-
! style="background-color:#efefef;" | [[23rd century]]
| [[2204]] || || || [[2232]] || || [[2260]] || || || [[2288]] || 
|-
! style="background-color:#efefef;" | [[24th century]]
| || || [[2328]] || || || [[2356]] || || || [[2384]] || 
|-
! style="background-color:#efefef;" | [[25th century]]
| || [[2412]] || || [[2440]] || || || [[2468]] || || || [[2496]]
|-
! style="background-color:#efefef;" | [[26th century]]
| [[2508]] || || || [[2536]] || || || [[2564]] || || || [[2592]]
|-
! style="background-color:#efefef;" | [[27th century]]
| [[2604]] || || || [[2632]] || || [[3rd millennium#27th century|2660]] || || || [[2688]] || 
|}

{| class="wikitable"
|+ 400-year cycle
|-
! 0–99
| 12 || 40 || 68 || 96
|-
! 100–199
| 108 || 136 || 164 || 192
|-
! 200–299
| 204 || 232 || 260 || 288
|-
! 300–399
| 328 || 356 || 384 ||
|}

===Julian Calendar===
Like all leap year types, the one starting with 1 January on a Sunday occurs exactly once in a [[solar cycle (calendar)|28-year cycle]] in the Julian calendar, i.e., in 3.57% of years. As the Julian calendar repeats after 28 years, it will also repeat after 700 years, i.e., 25 cycles. The formula gives the year's position in the cycle ((year + 8) mod 28) + 1).

{| class="wikitable"
|+ Julian leap years starting on Sunday
!scope=row| Decade
! 1st !! 2nd !! 3rd !! 4th !! 5th !! 6th !! 7th !! 8th !! 9th !! 10th
|-
! style="background-color:#efefef;" | [[15th century]]
| [[1408]] || || || [[1436]] || || || [[1464]] || || || [[1492]]
|-
! style="background-color:#efefef;" | [[16th century]]
| || [[1520]] || || || [[1548]] || || || [[1576]] || || 
|-
! style="background-color:#efefef;" | [[17th century]]
| [[1604]] || || || [[1632]] || || [[1660]] || || || [[1688]] || 
|-
! style="background-color:#efefef;" | 18th century
| || [[1716]] || || || [[1744]] || || || [[1772]] || || [[1800]]
|-
! style="background-color:#efefef;" | 19th century
| || || 1828 || || || 1856 || || || 1884 || 
|-
! style="background-color:#efefef;" | 20th century
| || 1912 || || 1940 || || || 1968 || || || 1996
|-
! style="background-color:#efefef;" | 21st century
| || || 2024 || || || 2052 || || 2080 || || 
|-
! style="background-color:#efefef;" | 22nd century
| 2108 || || || 2136 || || || 2164 || || || 2192
|}

== Holidays ==

=== International ===
* [[Valentine's Day]] falls on a [[Tuesday]]
* The leap day ([[February 29]]) falls on a [[Wednesday]]
* [[Grandparents' Day|World Day for Grandparents and the Elderly]] falls on its earliest possible date, [[July 22]]
* [[Halloween]] falls on a [[Wednesday]]
* [[Christmas Day]] falls on a [[Tuesday]]

=== Roman Catholic Solemnities ===
* [[Epiphany (holiday)|Epiphany]] falls on a [[Friday]]
* [[Candlemas]] falls on a [[Thursday]]
* [[Saint Joseph's Day]] falls on a [[Monday]]
* The [[Annunciation of Jesus]] falls on a [[Sunday]]
* The [[Nativity of John the Baptist]] falls on a [[Sunday]]
* The [[Solemnity of Saints Peter and Paul]] falls on a [[Friday]]
* The [[Transfiguration of Jesus]] falls on a [[Monday]]
* The [[Assumption of Mary]] falls on a [[Wednesday]]
* The [[Exaltation of the Holy Cross]] falls on a [[Friday]]
* [[All Saints' Day]] falls on a [[Thursday]]
* [[All Souls' Day]] falls on a [[Friday]]
* The [[Feast of Christ the King]] falls on [[November 25]] (or on [[October 28]] in versions of the calendar between 1925 and 1962)
* The [[First Sunday of Advent]] falls on [[December 2]]
* The [[Immaculate Conception]] falls on a [[Saturday]]
* [[Gaudete Sunday]] falls on [[December 16]]
* [[Rorate Sunday]] falls on [[December 23]]

=== Australia and New Zealand ===
* [[Australia Day]] falls on a [[Thursday]]
* [[Waitangi Day]] falls on a [[Monday]]
* [[Daylight saving]] ends on its earliest possible date, [[April 1]]
* [[ANZAC Day]] falls on a [[Wednesday]]
* [[Mother's Day]] falls on [[May 13]]
* [[Father's Day]] falls on [[September 2]]
* Daylight saving begins on its latest possible date, [[September 30]] in New Zealand and [[October 7]] in Australia – this is the only leap year where the period of standard time over the winter months lasts 26 weeks in New Zealand and 27 weeks in Australia (in all other leap years, it lasts only 25 weeks in New Zealand and 26 weeks in Australia)

=== British Isles ===
* [[Saint David's Day]] falls on a [[Thursday]]
* [[Mother's Day]] falls on [[March 4]], [[March 11]], [[March 18]], [[March 25]] or [[April 1]]
* [[Saint Patrick's Day]] falls on a [[Saturday]]
* [[Daylight saving]] begins on its earliest possible date, [[March 25]]
* [[Saint George's Day]] falls on a [[Monday]]
* [[Father's Day]] falls on [[June 17]]
* [[Orangeman's Day]] falls on a [[Thursday]]
* Daylight saving ends on [[October 28]]
* [[Guy Fawkes Night]] falls on a [[Monday]]
* [[Saint Andrew's Day]] falls on a [[Friday]]

=== Canada ===
* [[Daylight saving]] begins on [[March 11]]
* [[Mother's Day]] falls on [[May 13]]
* [[Victoria Day]] falls on [[May 21]]
* [[Father's Day]] falls on [[June 17]]
* [[Canada Day]] falls on a [[Sunday]]
* [[Labour Day (Canada)|Labour Day]] falls on [[September 3]]
* [[Thanksgiving Day (Canada)|Thanksgiving Day]] falls on its earliest possible date, [[October 8]]
* Daylight saving ends on [[November 4]]

=== United States ===
* [[Martin Luther King Jr. Day]] falls on [[January 16]]
* [[President's Day]] falls on [[February 20]]
* [[Daylight saving]] begins on [[March 11]]
* [[Mother's Day]] falls on [[May 13]]
* [[Memorial Day]] falls on [[May 28]]
* [[Father's Day]] falls on [[June 17]]
* [[Juneteenth]] falls on a [[Tuesday]]
* [[Independence Day (United States)|Independence Day]] falls on a [[Wednesday]]
* [[Labor Day (United States)|Labor Day]] falls on [[September 3]]
* [[Grandparents' Day]] falls on [[September 9]]
* [[Columbus Day]] falls on its earliest possible date, [[October 8]]
* Daylight saving ends on [[November 4]]
* [[Thanksgiving Day]] falls on its earliest possible date, [[November 22]]

==References==
{{Commons category}}
{{Reflist}}
{{List of calendars}}

{{DEFAULTSORT:Leap Year Starting On Sunday}}
[[Category:Gregorian calendar]]
[[Category:Julian calendar]]
[[Category:Sunday]]