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.
Common years starting on Thursday share this characteristic, but also have another in February.
Leap years starting on Sunday share this by having January, April and July three months apart from each other.
Common years starting on Sunday share this characteristic, in the months of February, March, and November.
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.