Occurrence
The following months have a Friday the 13th:
| Month | Years | Dominical letter |
|---|---|---|
| January | 1978, 1984, 1989, 1995, 2006, 2012, 2017, 2023 | A, AG |
| February | 1976, 1981, 1987, 1998, 2004, 2009, 2015, 2026 | D, DC |
| March | 1981, 1987, 1992, 1998, 2009, 2015, 2020, 2026 | D, ED |
| April | 1973, 1979, 1984, 1990, 2001, 2007, 2012, 2018 | G, AG |
| May | 1977, 1983, 1988, 1994, 2005, 2011, 2016, 2022 | B, CB |
| June | 1975, 1980, 1986, 1997, 2003, 2008, 2014, 2025 | E, FE |
| July | 1973, 1979, 1984, 1990, 2001, 2007, 2012, 2018 | G, AG |
| August | 1976, 1982, 1993, 1999, 2004, 2010, 2021, 2027 | C, DC |
| September | 1974, 1985, 1991, 1996, 2002, 2013, 2019, 2024 | F, GF |
| October | 1978, 1989, 1995, 2000, 2006, 2017, 2023, 2028 | A, BA |
| November | 1981, 1987, 1992, 1998, 2009, 2015, 2020, 2026 | D, ED |
| December | 1974, 1985, 1991, 1996, 2002, 2013, 2019, 2024 | F, GF |
This sequence given here for 2001–2028, follows a 28-year cycle from March 1, 1900 to February 28, 2100. The months with a Friday the 13th are determined by the Dominical letter (G, F, GF, etc.) of the year. Every month that begins on a Sunday will contain a Friday the 13th, and there is at least one Friday the 13th in every calendar year.
The longest period that can occur without a Friday the 13th is fourteen months, either from July to September the following common year (e.g. between 2001–02, 2012–13, and 2018–19), or from August to October the following leap year (e.g. between 1999–2000 or 2027–28).
Friday the 13th can occur as many as three times in a single year; either in February, March and November in an ordinary year (such as 2009), or January, April and July in leap years (such as 2012).
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Patterns for common years: Each Gregorian 400-year cycle contains 146,097 days (365 × 400 = 146,000 normal days, plus 97 leap days). 146,097 ÷ 7 = 20,871 weeks. Thus, each cycle contains the same pattern of days of the week (and thus the same pattern of Fridays that are on the 13th). The 13th day of the month is slightly more likely to be a Friday than any other day of the week. On average, there is a Friday the 13th once every 212.35 days (compared to Thursday the 13th, which occurs only once every 213.59 days). The distribution of the 13th day over the 4,800 months is as follows:
Read more about this topic: Friday The 13th Famous quotes containing the word occurrence:“One is absolutely sickened, not by the crimes that the wicked have committed, but by the punishments that the good have inflicted; and a community is infinitely more brutalised by the habitual employment of punishment than it is by the occasional occurrence of crime.” |