Friday the 13th is considered an unlucky day in Western superstition. It occurs when the 13th day of the month in the Gregorian calendar falls on a Friday, which happens at least once every year but can occur up to three times in the same year. Common years that begin in Thursday have three Friday the 13ths in February, March, and November, such as 2009, 2015, and 2026. Leap years that begin on Sunday (i.e. that follow Dominical Letter AG) such as 2012 and 2040, also have three Friday the 13ths in January, April, and July. The years 2001, 2002, 2004, 2006, 2007, 2013, 2017, 2018, 2019, 2020, 2023 and 2024 had two Friday the 13ths, as will 2029; 2003, 2005, 2008, 2010, 2011, 2014, 2016, 2021, and 2022 had only one Friday the 13th, as will 2025, 2027, and 2028.[1]
For a month to have a Friday the 13th, the 1st must be a Sunday.