Weekdays for December 13

2007: Thursday
2008: Saturday
2009: Sunday
2010: Monday
2011: Tuesday

2012: Thursday
2013: Friday
2014: Saturday
2015: Sunday
2016: Tuesday

2017: Wednesday
2018: Thursday
2019: Friday
2020: Sunday
2021: Monday

2022: Tuesday
2023: Wednesday
2024: Friday
2025: Saturday
2026: Sunday