Leap year starting on Wednesday

A leap year starting on Wednesday is any year with 366 days (i.e. it includes 29 February) that begins on Wednesday 1 January and ends on Thursday 31 December. Its dominical letters hence are ED. The most recent year of such kind was 2020, and the next one will be 2048 in the Gregorian calendar, or likewise, 2004 and 2032 in the obsolete Julian calendar, see below for more. ^[1]

Any leap year that starts on Wednesday has two Friday the 13ths: those two in this leap year occur in March and November. Common years starting on Thursday share this characteristic, but also have another in February.

Leap years starting on Sunday also share a similar characteristic to this type of leap year, three Friday the 13th's have a three month gap between them, the former two being in the common year preceding this type of leap year, those being September and December, and the latter being in this type of year, that being March. Leap years starting on Sunday share this by having January, April and July three months apart from each other.

This is the only leap year with three occurrences of Friday the 17th: those three in this leap year occur three months (13 weeks) apart: in January, April, and July. Common years starting on Sunday share this characteristic, in the months of February, March, and November.

From August of the common year preceding that year until October in this type of year is also the longest period (14 months) that occurs without a Tuesday the 13th, as in 2019-20. Common years starting on Saturday share this characteristic, from July of the year that precedes it to September in that type of year.

Calendars

Calendar for any leap year starting on Wednesday, presented as common in many English-speaking areas
January Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31	February Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29	March Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31	April Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
May Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31	June Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30	July Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31	August Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
September Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30	October Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31	November Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30	December Su Mo Tu We Th Fr Sa 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

ISO 8601-conformant calendar with week numbers for any leap year starting on Wednesday (dominical letter ED)
January Wk Mo Tu We Th Fr Sa Su 01 01 02 03 04 05 02 06 07 08 09 10 11 12 03 13 14 15 16 17 18 19 04 20 21 22 23 24 25 26 05 27 28 29 30 31	February Wk Mo Tu We Th Fr Sa Su 05 01 02 06 03 04 05 06 07 08 09 07 10 11 12 13 14 15 16 08 17 18 19 20 21 22 23 09 24 25 26 27 28 29	March Wk Mo Tu We Th Fr Sa Su 09 01 10 02 03 04 05 06 07 08 11 09 10 11 12 13 14 15 12 16 17 18 19 20 21 22 13 23 24 25 26 27 28 29 14 30 31	April Wk Mo Tu We Th Fr Sa Su 14 01 02 03 04 05 15 06 07 08 09 10 11 12 16 13 14 15 16 17 18 19 17 20 21 22 23 24 25 26 18 27 28 29 30
May Wk Mo Tu We Th Fr Sa Su 18 01 02 03 19 04 05 06 07 08 09 10 20 11 12 13 14 15 16 17 21 18 19 20 21 22 23 24 22 25 26 27 28 29 30 31	June Wk Mo Tu We Th Fr Sa Su 23 01 02 03 04 05 06 07 24 08 09 10 11 12 13 14 25 15 16 17 18 19 20 21 26 22 23 24 25 26 27 28 27 29 30	July Wk Mo Tu We Th Fr Sa Su 27 01 02 03 04 05 28 06 07 08 09 10 11 12 29 13 14 15 16 17 18 19 30 20 21 22 23 24 25 26 31 27 28 29 30 31	August Wk Mo Tu We Th Fr Sa Su 31 01 02 32 03 04 05 06 07 08 09 33 10 11 12 13 14 15 16 34 17 18 19 20 21 22 23 35 24 25 26 27 28 29 30 36 31
September Wk Mo Tu We Th Fr Sa Su 36 01 02 03 04 05 06 37 07 08 09 10 11 12 13 38 14 15 16 17 18 19 20 39 21 22 23 24 25 26 27 40 28 29 30	October Wk Mo Tu We Th Fr Sa Su 40 01 02 03 04 41 05 06 07 08 09 10 11 42 12 13 14 15 16 17 18 43 19 20 21 22 23 24 25 44 26 27 28 29 30 31	November Wk Mo Tu We Th Fr Sa Su 44 01 45 02 03 04 05 06 07 08 46 09 10 11 12 13 14 15 47 16 17 18 19 20 21 22 48 23 24 25 26 27 28 29 49 30	December Wk Mo Tu We Th Fr Sa Su 49 01 02 03 04 05 06 50 07 08 09 10 11 12 13 51 14 15 16 17 18 19 20 52 21 22 23 24 25 26 27 53 28 29 30 31

Applicable years

Gregorian Calendar

Leap years that begin on Wednesday, along with those starting on Tuesday, occur at a rate of approximately 14.43% (14 out of 97) of all total leap years in a 400-year cycle of the Gregorian calendar. Thus, their overall occurrence is 3.5% (14 out of 400).

For this kind of year, the corresponding ISO year has 53 weeks.

Gregorian leap years starting on Wednesday ^[1]

Decade	1st	2nd	3rd	4th	5th	6th	7th	8th	9th	10th
16th century	prior to first adoption (proleptic)									1592
17th century			1620		1648			1676
18th century		1716			1744			1772
19th century		1812		1840			1868			1896
20th century	1908			1936			1964			1992
21st century			2020		2048			2076
22nd century		2116			2144			2172
23rd century		2212		2240			2268			2296
24th century	2308			2336			2364			2392
25th century			2420		2448			2476
26th century		2516			2544			2572
27th century		2612		2640			2668			2696

400-year cycle

0–99	20	48	76
100–199	116	144	172
200–299	212	240	268	296
300–399	308	336	364	392

Julian Calendar

Like all leap year types, the one starting with 1 January on a Wednesday 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).

Julian leap years starting on Wednesday

Decade	1st	2nd	3rd	4th	5th	6th	7th	8th	9th	10th
15th century		1416			1444			1472		1500
16th century			1528			1556			1584
17th century		1612		1640			1668			1696
18th century			1724			1752		1780
19th century	1808			1836			1864			1892
20th century		1920			1948			1976
21st century	2004			2032		2060			2088
22nd century		2116			2144			2172		2200

Holidays

International

• Valentine's Day falls on a Friday
• World Day for Grandparents and the Elderly falls on July 26
• Halloween falls on a Saturday
• Christmas Day falls on a Friday

Roman Catholic Solemnities

• Epiphany falls on a Monday
• Candlemas falls on a Sunday
• Saint Joseph's Day falls on a Thursday
• The Annunciation of Jesus falls on a Wednesday
• The Nativity of John the Baptist falls on a Wednesday
• The Solemnity of Saints Peter and Paul falls on a Monday
• The Transfiguration of Jesus falls on a Thursday
• The Assumption of Mary falls on a Saturday
• The Exaltation of the Holy Cross falls on a Monday
• All Saints' Day falls on a Sunday
• All Souls' Day falls on a Monday
• The Feast of Christ the King falls on November 22 (or on its earliest possible date of October 25 in versions of the calendar between 1925 and 1962)
• The First Sunday of Advent falls on November 29
• The Immaculate Conception falls on a Tuesday
• Gaudete Sunday falls on December 13
• Rorate Sunday falls on December 20

Australia and New Zealand

• Australia Day falls on a Sunday
• Waitangi Day falls on a Thursday
• Daylight saving ends on April 5
• ANZAC Day falls on a Saturday
• Mother's Day falls on May 10
• Father's Day falls on September 6
• Daylight saving begins on September 27 in New Zealand and October 4 in Australia

British Isles

• Saint David's Day falls on a Sunday
• Mother's Day falls on its earliest possible date of March 1, or on March 8, March 15, March 22 or March 29
• Saint Patrick's Day falls on a Tuesday
• Daylight saving begins on March 29
• Saint George's Day falls on a Thursday
• Father's Day falls on its latest possible date, June 21
• Orangeman's Day falls on a Sunday
• Daylight saving ends on its earliest possible date, October 25
• Guy Fawkes Night falls on a Thursday
• Saint Andrew's Day falls on a Monday

Canada

• Daylight saving begins on its earliest possible date, March 8
• Mother's Day falls on May 10
• Victoria Day falls on its earliest possible date, May 18
• Father's Day falls on its latest possible date, June 21. This is the only leap year when Victoria Day and Labour Day are 34 days apart. They are 27 days apart in all other leap years.
• Canada Day falls on a Wednesday
• Labour Day falls on its latest possible date, September 7 – this is the only leap year when Victoria Day and Labour Day are sixteen weeks apart (they are fifteen weeks apart in all other leap years)
• Thanksgiving Day falls on October 12
• Daylight saving ends on its earliest possible date, November 1 -This is the only leap year when Labour Day and the end of Daylight Saving Time are 55 days apart. They are 62 days apart in all other leap years

United States

• Martin Luther King Jr. Day falls on January 20
• President's Day falls on February 17
• Daylight saving begins on its earliest possible date, March 8
• Mother's Day falls on May 10
• Memorial Day falls on its earliest possible date, May 25
• Juneteenth falls on a Friday
• Father's Day falls on its latest possible date, June 21. This is the only leap year when Memorial Day and Father’s Day are 27 days apart. They are 20 days apart in all other leap years. This is also the only leap year when the start of Daylight Saving Time and Father’s Day are 15 weeks apart. They are 14 weeks apart in all other leap years
• Independence Day falls on a Saturday
• Labor Day falls on its latest possible date, September 7 – this is the only leap year when Memorial Day and Labor Day are fifteen weeks apart (they are fourteen weeks apart in all other leap years). This is the only leap year when the start of Daylight Saving Time and Labor Day are 183 days apart. They are 176 days apart in all other leap years.
• Grandparents' Day falls on its latest possible date, September 13. This is the only leap year when Memorial Day and Grandparent’s Day are 111 days apart. They are 104 days apart in all other leap years. This is also the only leap year when the start of Daylight Saving Time and Grandparent’s Day are 27 weeks apart. They are 26 weeks apart in all other leap years
• Columbus Day falls on October 12
• Daylight saving ends on its earliest possible date, November 1. This is the only leap year when Labor Day and the end of Daylight Saving Time are 55 days apart. They are 62 days apart in all other leap years. This is also the only leap year when Father’s Day and the end of Daylight Saving Time are 19 weeks apart. They are 20 weeks apart in all other leap years. This is also the only leap year when Grandparent’s Day and the end of Daylight Saving Time are 7 weeks apart. They are 8 weeks apart in all other leap years
• Election Day falls on November 3, its 2nd earliest election day, only surpassed by November 2.
• Thanksgiving Day falls on November 26

References

1. Robert van Gent (2017). "The Mathematics of the ISO 8601 Calendar". Utrecht University, Department of Mathematics. Retrieved 20 July 2017.