When does the dog days start and end?

The third Geng day after the summer solstice solar terms begins and the first Geng day after the autumn solar terms begins ends. Dog days generally begin on the third Geng day after the summer solstice solar terms and end on the first Geng day after the autumn solar terms. Specifically, the initial period is from long summer to the day before the third Geng Day in the future to the first Geng Day after beginning of autumn, the middle period is from the first Geng Day after beginning of autumn to the day before the second Geng Day after beginning of autumn, and the final period is from the second Geng Day after beginning of autumn to the day before the first Geng Day after beginning of autumn.