The first nine days of the month of Av (Monday, July 28 through Tuesday, August 5) are days of acute mourning for the destruction of the first and second Holy Temples. Among other observances, during this time we refrain from eating meat or drinking wine (except on Shabbat), swimming or bathing for pleasure, remodeling or expanding a home and buying new clothes.
The Fast of Tisha B'Av begins on Monday, August 4th at 8:11 pm and concludes the next day at 8:36 pm (times local to the Clear Lake area).