A leap year that begins on a Thursday is a 366-day year in the Gregorian calendar whose January 1 falls on a Thursday. In this configuration February has 29 days and the extra day shifts the weekday of subsequent years by two days. Because of that shift and the arrangement of month lengths, this type of year has a distinctive pattern of weekdays for fixed dates, recurring holidays and notable weekday coincidences.

Key characteristics

When January 1 is a Thursday in a leap year:

  • Start and end days: The year starts on Thursday and ends on Friday (December 31 is Friday), so the following year begins on Saturday.
  • Doomsday: Using the Doomsday rule, the year's anchor weekday (doomsday) is Sunday. In leap years the dates January 4 and February 29 share the doomsday weekday, so both fall on Sunday in this configuration.
  • Friday the 13ths: This leap-year type produces two Friday the 13ths, occurring in February and August.
  • Monthly anchors: Certain easy-to-remember dates fall on the doomsday weekday (for example 4/4, 6/6, 8/8, 10/10 and 12/12 will be on Sunday), which makes calculating weekdays of other dates straightforward.

Holidays and common observances (example mapping)

The weekday on which movable and fixed holidays fall depends on this starting weekday. As an illustrative list for countries that follow standard U.S. federal observance dates: Martin Luther King Jr. Day (third Monday in January) falls on January 19; Valentine’s Day is on a Saturday; Presidents' Day (third Monday in February) is February 16; the leap day, February 29, is on a Sunday; St. Patrick’s Day is on a Wednesday; Mother’s Day (second Sunday in May) is May 9; Memorial Day (last Monday in May) falls on its latest possible date, May 31; Father’s Day (third Sunday in June) is June 20; Independence Day (July 4) is on a Sunday; Labor Day (first Monday in September) is September 6; Columbus Day (second Monday in October) is October 11; Halloween (October 31) is on a Sunday; Veterans Day (November 11) is on a Thursday; Thanksgiving (fourth Thursday in November) is November 25; and Christmas (December 25) is on a Saturday.

Examples and calendar context

Examples of leap years that began on a Thursday in the modern Gregorian calendar include 1920, 1948, 1976, 2004, 2032, as well as later occurrences such as 2060 and 2088. The classification relates to the broad rules of the Gregorian calendar and the particular weekday Thursday, referenced here as Thursday.

How and why the pattern recurs

Calendar patterns repeat according to cycles that depend on leap-year rules. For many practical purposes a 28-year cycle governs repetition of weekday patterns among non-century spans, but the Gregorian calendar's full repetition requires a 400-year cycle because of the century leap-year exceptions. Techniques such as the Doomsday algorithm let one quickly determine the weekday of any date in a year that begins on Thursday: since the doomsday is Sunday, dates tied to the doomsday (for example 4/4, 6/6, 8/8, 10/10 and 12/12) fall on Sunday, and other dates can be offset from those anchors.

  • This leap-year configuration is one of the patterns that produces exactly two Friday the 13ths; other leap-year starting weekdays that produce two Friday the 13ths include the leap year starting on Monday and the leap year starting on Wednesday.
  • Because February 29 and January 4 are doomsdays in a leap year, any calculation of moveable feasts or weekday-based observances can often be simplified by referencing those anchor dates.

Understanding the specific layout of a leap year starting on Thursday is useful for planning, historical research, and calendar computations. For practical calendar creation or conversion, applying the Doomsday algorithm or consulting a perpetual calendar for the Gregorian system will confirm the weekday for any date in such years.