Editing Leap year starting on Thursday

{{Short description|none}}
A '''leap year starting on Thursday''' is any year with 366 days (i.e. it includes 29 February) that begins on [[Thursday]] 1 January, and ends on [[Friday]] 31 December. Its [[dominical letter]]s hence are '''DC'''. The most recent year of such kind was [[2004]], and the next one will be [[2032]] 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, [[2016]] and [[2044]] in the obsolete [[Julian calendar]].

This is the only leap year with three occurrences of [[Friday the 13th#Tuesday the 13th in Hispanic and Greek culture|Tuesday 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 Monday|Common years starting on Monday]] share this characteristic, in the months of February, March, and November.

Any leap year that starts on [[Thursday]] has two [[Friday the 13th]]s: those two in this leap year [[February 13|occur in February]] and [[August 13|August]]. This is also the only year in which February has five Sundays, as the leap day adds that extra Sunday.

This year has three months (February, May and August) which begin on a weekend-day.



== Calendars ==
<!-- To avoid arbitrary years, use the most recent year of this type. 2004 was the most recent year of this type. -->
{{calendar|year=2004|show_year=off|title=Calendar for any [[leap year]] starting on Thursday,<br />presented as common in many English-speaking areas}}

{{calendar|year=2004|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 Thursday (dominical letter DC)}}

== Applicable years ==
=== Gregorian Calendar ===
Leap years that begin on Thursday, along with those [[Leap year starting on Monday|starting on Monday]] and [[Leap year starting on Saturday|Saturday]], 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).

For this kind of year, the corresponding [[ISO week date|ISO year]] has 53 weeks, and the ISO week 10 (which begins March 1) and all subsequent ISO weeks occur earlier than in all other years, and exactly one week earlier than [[Common year starting on Friday|common years starting on Friday]], for example, June 20 falls on week 24 in common years starting on Friday, but on week 25 in leap years starting on Thursday, despite falling on Sunday in both types of year. That means that moveable holidays may occur one calendar week later than otherwise possible, e.g. Gregorian [[Easter]] Sunday in week 17 in years when it falls on April 25 and which are also leap years, falling on week 16 in common years.{{#tag:ref|Leap years when Easter Sunday falls on April 25 are only possible years when Easter Sunday can fall on week 17.}}

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

! style="background-color:#efefef;" | [[17th century]]
| [[1604]] || || || [[1632]] || || [[1660]] || || || [[1688]] || 
|-
! style="background-color:#efefef;" | [[18th century]]
| || || [[1728]] || || || [[1756]] || || || [[1784]] || 
|-
! style="background-color:#efefef;" | [[19th century]]
| || || [[1824]] || || || [[1852]] || || [[1880]] || || 
|-
! style="background-color:#efefef;" | [[20th century]]
| || [[1920]] || || || [[1948]] || || || [[1976]] || || 
|-
! style="background-color:#efefef;" | [[21st century]]
| [[2004]] || || || [[2032]] || || [[2060]] || || || [[2088]] || 
|-
! style="background-color:#efefef;" | [[22nd century]]
| || || [[2128]] || || || [[2156]] || || || [[2184]] ||
|-
! style="background-color:#efefef;" | [[23rd century]]
| || || [[2224]] || || || [[2252]] || || [[2280]] || || 
|-
! style="background-color:#efefef;" | [[24th century]]
| || [[2320]] || || || [[2348]] || || || [[2376]] || || 
|-
! style="background-color:#efefef;" | [[25th century]]
| [[2404]] || || || [[2432]] || || [[2460]] || || || [[2488]] || 
|-
! style="background-color:#efefef;" | [[26th century]]
| || || 2528 || || || 2556 || || || 2584 ||
|-
! style="background-color:#efefef;" | [[27th century]]
| || || 2624|| || || 2652 || || 2680 || ||
|}

{| class="wikitable"
|+ 400-year cycle
|-
! 0–99
| 4 || 32 || 60 || 88
|-
! 100–199
| 128 || 156 || 184 ||
|-
! 200–299
| 224 || 252 || 280 ||
|-
! 300–399
| 320 || 348 || 376 ||
|}

=== Julian Calendar ===
Like all leap year types, the one starting with 1 January on a Thursday 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 Thursday
!scope=row| Decade
! 1st !! 2nd !! 3rd !! 4th !! 5th !! 6th !! 7th !! 8th !! 9th !! 10th
|-
! style="background-color:#efefef;" | [[15th century]]
| || || [[1428]] || || || [[1456]] || || || [[1484]] || 
|-
! style="background-color:#efefef;" | [[16th century]]
| || [[1512]] || || [[1540]] || || || [[1568]] || || || [[1596]]
|-
! style="background-color:#efefef;" | [[17th century]]
| || || [[1624]] || || || [[1652]] || || [[1680]] || || 
|-
! style="background-color:#efefef;" | 18th century
| 1708 || || || 1736 || || || 1764 || || || 1792
|-
! style="background-color:#efefef;" | 19th century
| || 1820 || || || 1848 || || || 1876 || || 
|-
! style="background-color:#efefef;" | 20th century
| 1904 || || || 1932 || || 1960 || || || 1988 || 
|-
! style="background-color:#efefef;" | 21st century
| || 2016 || || || 2044 || || || 2072 || || 2100
|-
! style="background-color:#efefef;" | 22nd century
| || || 2128 || || || 2156 || || || 2184 ||
|}
{{Commons category}}

== Holidays ==

=== International ===
* [[Valentine's Day]] falls on a [[Saturday]]
* The leap day ([[February 29]]) falls on a [[Sunday]]
* [[Grandparents' Day|World Day for Grandparents and the Elderly]] falls on [[July 25]]
* [[Halloween]] falls on a [[Sunday]]
* [[Christmas Day]] falls on a [[Saturday]]

=== Roman Catholic Solemnities ===
* [[Epiphany (holiday)|Epiphany]] falls on a [[Tuesday]]
* [[Candlemas]] falls on a [[Monday]]
* [[Saint Joseph's Day]] falls on a [[Friday]]
* The [[Annunciation of Jesus]] falls on a [[Thursday]]
* The [[Nativity of John the Baptist]] falls on a [[Thursday]]
* The [[Solemnity of Saints Peter and Paul]] falls on a [[Tuesday]]
* The [[Transfiguration of Jesus]] falls on a [[Friday]]
* The [[Assumption of Mary]] falls on a [[Sunday]]
* The [[Exaltation of the Holy Cross]] falls on a [[Tuesday]]
* [[All Saints' Day]] falls on a [[Monday]]. This is the only year when All Saints Day falls in ISO week 45. They fall in ISO week 44 in all other years.
* [[All Souls' Day]] falls on a [[Tuesday]]
* The [[Feast of Christ the King]] falls on [[November 21]] (or on its latest possible date of [[October 31]] in versions of the calendar between 1925 and 1962)
* The [[First Sunday of Advent]] falls on [[November 28]]
* The [[Immaculate Conception]] falls on a [[Wednesday]]
* [[Gaudete Sunday]] falls on [[December 12]]
* [[Rorate Sunday]] falls on [[December 19]]

=== Australia and New Zealand ===
* [[Australia Day]] falls on a [[Monday]]
* [[Waitangi Day]] falls on a [[Friday]]
* [[Daylight saving]] ends on [[April 4]]
* [[ANZAC Day]] falls on a [[Sunday]], and in some years coincides with [[Easter Sunday]] falling on its latest possible date
* [[Mother's Day]] falls on [[May 9]]
* [[Father's Day]] falls on [[September 5]]
* Daylight saving begins on [[September 26]] in New Zealand and [[October 3]] in Australia

=== British Isles ===
* [[Saint David's Day]] falls on a [[Monday]]. This is the only year when Saint David's Day falls in ISO week 10. They fall in ISO week 9 in all other years
* [[Mother's Day]] falls on [[March 7]], [[March 14]], [[March 21]], [[March 28]] or on its latest possible date of [[April 4]]
* [[Daylight saving]] begins on [[March 28]] 
* [[Saint Patrick's Day]] falls on a [[Wednesday]]
* [[Saint George's Day]] falls on a [[Friday]], and in some years coincides with [[Good Friday]] falling on its latest possible date
* [[Father's Day]] falls on [[June 20]]
* [[Orangeman's Day]] falls on a [[Monday]]. This is the only year when Orangeman's Day falls in ISO week 29. They fall in ISO week 28 in all other years
* [[Daylight saving]] ends on its latest possible date, [[October 31]]. This is the only year when Daylight Saving Time ends in ISO week 44. They end in ISO week 43 in all other years
* [[Guy Fawkes Night]] falls on a [[Friday]]
* [[Saint Andrew's Day]] falls on a [[Tuesday]]

=== Canada ===
* [[Daylight saving]] begins on its latest possible date, [[March 14]]. This is the only year when Daylight Saving Time begins in ISO week 11. They begin in ISO week 10 in all other years.
* [[Mother's Day]] falls on [[May 9]]
* [[Victoria Day]] falls on its latest possible date, [[May 24]]. This is the only year when Victoria Day falls in ISO week 22. They fall in ISO week 21 in all other years. This is also the only year when Labour Day that precedes this type of year to Victoria Day in this type of year are 38 weeks apart. They are 37 weeks apart in all other years. This is also the only year when Father's Day that precedes this type of year to Victoria Day in this type of year are 344 days apart. They are 337 days apart in all other years.
* [[Father's Day]] falls on [[June 20]]
* [[Canada Day]] falls on a [[Thursday]]
* [[Labour Day (Canada)|Labour Day]] falls on [[September 6]]
* [[Thanksgiving Day (Canada)|Thanksgiving Day]] falls on [[October 11]]
* Daylight saving ends on its latest possible date, [[November 7]]. This is the only year when Daylight Saving Time ends in ISO week 45. They end in ISO week 44 in all other years.

=== United States ===
* [[Martin Luther King Jr. Day]] falls on [[January 19]]
* [[President's Day]] falls on [[February 16]]
* [[Daylight saving]] begins on its latest possible date, [[March 14]]. This is the only year when Daylight Saving Time begins in ISO week 11. They begin in ISO week 10 in all other years. This is also the only type of year where Labor Day that precedes this type of year to start of Daylight Saving Time is 195 days apart. They are 188 days apart in all other years. This is also the only type of year where Grandparent's Day that precedes this type of year to start of Daylight Saving Time is 27 weeks apart. They are 26 weeks apart in all other years. This is also the only type of year where Father's Day that precedes this type of year to start of Daylight Saving Time is 39 weeks apart. They are 38 weeks apart in all other years.
* [[Mother's Day]] falls on [[May 9]]
* [[Memorial Day]] falls on its latest possible date, [[May 31]]. This is the only year when Memorial Day falls in ISO week 23. They fall in ISO week 22 in all other years. This is also the only type of year where Labor Day that precedes this type of year to Memorial Day in this type of year are 39 weeks apart. They are 38 weeks apart in all other years. This is also the only type of year where Grandparent's Day that precedes this type of year to Memorial Day in this type of year are 267 days apart. They are 260 days apart in all other years. This is also the only type of year where Father's Day that precedes this type of year to Memorial Day in this type of year is 351 days apart. They are 344 days apart in all other years. 
* [[Juneteenth]] falls on a [[Saturday]]
* [[Father's Day]] falls on [[June 20]]
* [[Independence Day (United States)|Independence Day]] falls on a [[Sunday]]
* [[Labor Day (United States)|Labor Day]] falls on [[September 6]]
* [[Grandparents' Day]] falls on [[September 12]]
* [[Columbus Day]] falls on [[October 11]]
* [[Election Day (United States)|Election Day]] falls on its earliest possible date, [[November 2]]. This is the only leap year to have Election Day fall during Daylight Saving Time.
* Daylight saving ends on its latest possible date, [[November 7]]. This is the only year when Daylight Saving Time ends in ISO week 45. They end in ISO week 44 in all other years 
* [[Thanksgiving Day]] falls on [[November 25]]

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

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