When Is Tu B'Av 2024. The fast of tisha b'av 2024 (the ninth of av) begins at sundown on august 12, 2024, and concludes at nightfall on august 13, 2024. Coming so soon after tisha b’av, the radical transition from a mood of sadness to that of joy is doubly significant.
Tu b’av is celebrated every year on the 15th day of av. Tu b’av, the 15th day of av, is both an ancient and modern holiday.