Editing Leap year starting on Monday

{{Short description|none}}
A '''leap year starting on Monday''' is any year with 366 days (i.e. it includes [[February 29|29 February]]) that begins on [[Monday]], 1 January, and ends on [[Leap year starting on Tuesday|Tuesday]], 31 December. Its [[dominical letter]]s hence are '''GF'''. The most recent year of such kind was [[2024]], and the next one will be 2052 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, [[2008]] and [[2036]] in the obsolete [[Julian calendar]].

Any leap year that starts on [[Monday]] has two [[Friday the 13th]]s: those two in this leap year [[September 13|occur in September]] and [[December 13|December]]. [[Common year starting on Tuesday|Common years starting on Tuesday]] share this characteristic.

This year has three months (June, September and December) which begin on a weekend-day.

== Calendars ==
<!-- To avoid arbitrary years, use the most recent year of this type. 2024 was the most recent year of this type. -->
{{calendar|year=2024|show_year=off|title=Calendar for any [[leap year]] starting on Monday,<br />presented as common in many English-speaking areas}}

{{calendar|year=2024|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 Monday (dominical letter GF)}}

== Applicable years ==
=== Gregorian Calendar ===
Leap years that begin on Monday, along with those [[Leap year starting on Saturday|starting on Saturday]] and [[Leap year starting on Thursday|Thursday]], occur least frequently: 13 out of 97 (≈ 13.4%) total leap years in a 400-year cycle of the [[Gregorian calendar]]. Their overall frequency is thus 3.25% (13 out of 400) of years.

{| class="wikitable"
|+ Gregorian leap years starting on Monday<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)''|| || [[1596]]
|-
![[17th century]]
|
|
|[[1624]]
|
|
|[[1652]]
|
|[[1680]]
|
|
|-
! style="background-color:#efefef;" | [[18th century]]
|  || [[1720]] ||  ||  || [[1748]] ||  ||  || [[1776]] ||  || 
|-
! style="background-color:#efefef;" | [[19th century]]
|  || [[1816]] ||  ||  || [[1844]] ||  ||  || [[1872]] ||  || 
|-
! 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]]
|  || [[2120]] ||  ||  || [[2148]] ||  ||  || [[2176]] ||  ||
|-
! style="background-color:#efefef;" | [[23rd century]]
|  || [[2216]] ||  ||  || [[2244]] ||  ||  || [[2272]] ||  || 
|-
! style="background-color:#efefef;" | [[24th century]]
| || [[2312]] ||  || [[2340]] ||  ||  || [[2368]] ||  ||  || [[2396]]
|-
! style="background-color:#efefef;" | [[25th century]]
|  ||  || [[2424]] ||  ||  || [[2452]] ||  || [[2480]] ||  || 
|-
! style="background-color:#efefef;" | [[26th century]]
|  || 2520 ||  ||  || 2548 ||  ||  || 2576 ||  ||
|-
! style="background-color:#efefef;" | [[27th century]]
|  || 2616 ||  ||  || 2644 ||  ||  || 2672 ||  || 
|}

{| class="wikitable"
|+ 400-year cycle
|-
! 0–99
| 24 || 52 || 80 ||
|-
! 100–199
| 120 || 148 || 176 ||
|-
! 200–299
| 216 || 244 || 272 ||
|-
! 300–399
| 312 || 340 || 368 || 396
|}

=== Julian Calendar ===
Like all leap year types, the one starting with 1 January on a Monday occurs exactly once in a [[solar cycle|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).

{| class="wikitable"
|+ Julian leap years starting on Monday
!scope=row| Decade
! 1st !! 2nd !! 3rd !! 4th !! 5th !! 6th !! 7th !! 8th !! 9th !! 10th
|-
! style="background-color:#efefef;" | [[14th century]]
| [[1308]] ||  ||  || [[1336]] ||  ||  || [[1364]] ||  ||  ||[[1392]]
|-
! style="background-color:#efefef;" | [[15th century]]
|  || [[1420]] ||  ||  || [[1448]] ||  ||  || [[1476]] ||  || 
|-
! style="background-color:#efefef;" | [[16th century]]
| [[1504]] ||  ||  || [[1532]] ||  || [[1560]] ||  ||  || [[1588]] || 
|-
! style="background-color:#efefef;" | [[17th century]]
|  || [[1616]] ||  ||  || [[1644]] ||  ||  || [[1672]] ||  || [[1700]]
|-
! style="background-color:#efefef;" | 18th century
|  ||  || [[1728]] ||  ||  || [[1756]] ||  ||  || [[1784]] || 
|-
! style="background-color:#efefef;" | 19th century
|  || [[1812]] ||  || [[1840]] ||  ||  || [[1868]] ||  ||  || [[1896]]
|-
! style="background-color:#efefef;" | 20th century
|  ||  || 1924 ||  ||  || 1952 ||  || 1980 ||  || 
|-
! style="background-color:#efefef;" | 21st century
| 2008 ||  ||  || 2036 ||  ||  || 2064 ||  ||  || 2092
|-
! style="background-color:#efefef;" | 22nd century
|  || 2120 ||  ||  || 2148 ||  ||  || 2176 ||  ||
|}

== Holidays ==

=== International ===
* [[Valentine's Day]] falls on a [[Wednesday]]
* The leap day ([[February 29]]) falls on a [[Thursday]]
* [[Grandparents' Day|World Day for Grandparents and the Elderly]] falls on its latest possible date, [[July 28]]
* [[Halloween]] falls on a [[Thursday]]
* [[Christmas Day]] falls on a [[Wednesday]]

=== Roman Catholic Solemnities ===
* [[Epiphany (holiday)|Epiphany]] falls on a [[Saturday]] or, in places when it is transferred to a Sunday, January 7
* [[Candlemas]] falls on a [[Friday]]
* [[Saint Joseph's Day]] falls on a [[Tuesday]]
* The [[Annunciation of Jesus]] falls on a [[Monday]]
* The [[Nativity of John the Baptist]] falls on a [[Monday]]
* The [[Solemnity of Saints Peter and Paul]] falls on a [[Saturday]]
* The [[Transfiguration of Jesus]] falls on a [[Tuesday]]
* The [[Assumption of Mary]] falls on a [[Thursday]]
* The [[Exaltation of the Holy Cross]] falls on a [[Saturday]]
* [[All Saints' Day]] falls on a [[Friday]]
* [[All Souls' Day]] falls on a [[Saturday]]
* The [[Feast of Christ the King]] falls on [[November 24]] (or on [[October 27]] in versions of the calendar between 1925 and 1962)
* The [[First Sunday of Advent]] falls on [[December 1]]
* The [[Immaculate Conception]] falls on a [[Sunday]], thus transferred to Monday, December 9.
* [[Gaudete Sunday]] falls on [[December 15]]
* [[Rorate Sunday]] falls on [[December 22]]

=== Australia and New Zealand ===
* [[Australia Day]] falls on a [[Friday]]
* [[Waitangi Day]] falls on a [[Tuesday]]
* [[Daylight saving]] ends on its latest possible date, [[April 7]] – the period of daylight saving which ends on [[April 7]] of a leap year starting on Monday is the only period ending in any year to last 27 weeks in Australia and 28 weeks in New Zealand; in all other instances, the period of daylight saving lasts only 26 weeks in Australia and 27 weeks in New Zealand
* [[ANZAC Day]] falls on a [[Thursday]]
* [[Mother's Day]] falls on [[May 12]]
* [[Father's Day]] falls on its earliest possible date, [[September 1]]
* Daylight saving begins on [[September 29]] in New Zealand and [[October 6]] in Australia

=== British Isles ===
* [[Saint David's Day]] falls on a [[Friday]]
* [[Mother's Day]] falls on [[March 3]], [[March 10]], [[March 17]], [[March 24]] or [[March 31]]
* [[Saint Patrick's Day]] falls on a [[Sunday]]
* [[Daylight saving]] begins on its latest possible date, [[March 31]]
* [[Saint George's Day]] falls on a [[Tuesday]]
* [[Father's Day]] falls on [[June 16]]
* [[Orangeman's Day]] falls on a [[Friday]]
* Daylight saving ends on [[October 27]]
* [[Guy Fawkes Night]] falls on a [[Tuesday]]
* [[Saint Andrew's Day]] falls on a [[Saturday]]

=== Canada ===
* [[Daylight saving]] begins on [[March 10]]
* [[Mother's Day]] falls on [[May 12]]
* [[Victoria Day]] falls on [[May 20]]
* [[Father's Day]] falls on [[June 16]]
* [[Canada Day]] falls on a [[Monday]]
* [[Labour Day (Canada)|Labour Day]] falls on [[September 2]]
* [[Thanksgiving Day (Canada)|Thanksgiving Day]] falls on its latest possible date, [[October 14]]
* Daylight saving ends on [[November 3]]

=== United States ===
* [[Martin Luther King Jr. Day]] falls on its earliest possible date, [[January 15]]
* [[President's Day]] falls on [[February 19]]
* [[Daylight saving]] begins on [[March 10]]
* [[Mother's Day]] falls on [[May 12]]
* [[Memorial Day]] falls on [[May 27]]
* [[Father's Day]] falls on [[June 16]]
* [[Juneteenth]] falls on a [[Wednesday]]
* [[Independence Day (United States)|Independence Day]] falls on a [[Thursday]]
* [[Labor Day (United States)|Labor Day]] falls on [[September 2]]
* [[Grandparents' Day]] falls on [[September 8]]
* [[Columbus Day]] falls on its latest possible date, [[October 14]] (this is the only year when Martin Luther King Jr. Day and Columbus Day are 39 weeks apart) They are 38 weeks apart in all other years
* Daylight saving ends on [[November 3]]
* [[Election Day (United States)|Election Day]] falls on [[November 5]]
* [[Thanksgiving Day]] falls on its latest possible date, [[November 28]] (this is also the only year when Martin Luther King Jr. Day and Thanksgiving are 318 days apart) They are 311 days apart in all other years

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

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