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 Monday, Wednesday or Thursday 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.

In this leap year, Martin Luther King Jr. Day is on January 20, Valentine’s Day is on a Friday, President's Day is on February 17, the leap day is on a Saturday, Saint Patrick’s Day is on a Tuesday, Memorial Day is on its earliest possible date, May 25, Juneteenth is on a Friday, U.S. Independence Day is on a Saturday, Labor Day is on its latest possible date, September 7, Halloween is on a Saturday, Thanksgiving is on November 26, and Christmas is on a Friday. Also like a common year starting on Thursday, this leap year is the only one where Memorial Day and Labor Day are not 14 weeks (98 days) apart: they are 15 weeks (105 days) apart in this leap 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
01020304
05060708091011
12131415161718
19202122232425
262728293031  
 
February
Su Mo Tu We Th Fr Sa
01
02030405060708
09101112131415
16171819202122
23242526272829
 
March
Su Mo Tu We Th Fr Sa
01020304050607
08091011121314
15161718192021
22232425262728
293031  
 
April
Su Mo Tu We Th Fr Sa
01020304
05060708091011
12131415161718
19202122232425
2627282930  
 
May
Su Mo Tu We Th Fr Sa
0102
03040506070809
10111213141516
17181920212223
24252627282930
31  
June
Su Mo Tu We Th Fr Sa
010203040506
07080910111213
14151617181920
21222324252627
282930  
 
July
Su Mo Tu We Th Fr Sa
01020304
05060708091011
12131415161718
19202122232425
262728293031  
 
August
Su Mo Tu We Th Fr Sa
01
02030405060708
09101112131415
16171819202122
23242526272829
3031  
September
Su Mo Tu We Th Fr Sa
0102030405
06070809101112
13141516171819
20212223242526
27282930  
 
October
Su Mo Tu We Th Fr Sa
010203
04050607080910
11121314151617
18192021222324
25262728293031
 
November
Su Mo Tu We Th Fr Sa
01020304050607
08091011121314
15161718192021
22232425262728
2930  
 
December
Su Mo Tu We Th Fr Sa
0102030405
06070809101112
13141516171819
20212223242526
2728293031  
 
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 0102030405
02 06070809101112
03 13141516171819
04 20212223242526
05 2728293031  
   
February
Wk Mo Tu We Th Fr Sa Su
05 0102
06 03040506070809
07 10111213141516
08 17181920212223
09 242526272829
   
March
Wk Mo Tu We Th Fr Sa Su
09 01
10 02030405060708
11 09101112131415
12 16171819202122
13 23242526272829
14 3031  
April
Wk Mo Tu We Th Fr Sa Su
14 0102030405
15 06070809101112
16 13141516171819
17 20212223242526
18 27282930  
   
May
Wk Mo Tu We Th Fr Sa Su
18 010203
19 04050607080910
20 11121314151617
21 18192021222324
22 25262728293031
   
June
Wk Mo Tu We Th Fr Sa Su
23 01020304050607
24 08091011121314
25 15161718192021
26 22232425262728
27 2930  
   
July
Wk Mo Tu We Th Fr Sa Su
27 0102030405
28 06070809101112
29 13141516171819
30 20212223242526
31 2728293031  
   
August
Wk Mo Tu We Th Fr Sa Su
31 0102
32 03040506070809
33 10111213141516
34 17181920212223
35 24252627282930
36 31  
September
Wk Mo Tu We Th Fr Sa Su
36 010203040506
37 07080910111213
38 14151617181920
39 21222324252627
40 282930  
   
October
Wk Mo Tu We Th Fr Sa Su
40 01020304
41 05060708091011
42 12131415161718
43 19202122232425
44 262728293031  
   
November
Wk Mo Tu We Th Fr Sa Su
44 01
45 02030405060708
46 09101112131415
47 16171819202122
48 23242526272829
49 30  
December
Wk Mo Tu We Th Fr Sa Su
49 010203040506
50 07080910111213
51 14151617181920
52 21222324252627
53 28293031  
   

Applicable years

Gregorian Calendar

Leap years that begin on Wednesday, like those that start 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. Their overall occurrence is thus 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 1st2nd3rd4th5th6th7th8th9th10th
17th century 162016481676
18th century 171617441772
19th century 1812184018681896
20th century 1908193619641992
21st century 202020482076
22nd century 211621442172
23rd century 2212224022682296
24th century 2308233623642392
25th century 242024482476
26th century 251625442572
27th century 2612264026682696

400 year cycle

century 1: 20, 48, 76

century 2: 116, 144, 172

century 3: 212, 240, 268, 296

century 4: 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 1st2nd3rd4th5th6th7th8th9th10th
15th century 1416144414721500
16th century 152815561584
17th century 1612164016681696
18th century 172417521780
19th century 1808183618641892
20th century 192019481976
21st century 2004203220602088
22nd century 2116214421722200
Wikimedia Commons has media related to Leap years starting on Wednesday and ending on Thursday.

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