The Solemnity of the Blessed Virgin Mary is 15 August. Since the date falls on a Monday this year, it is NOT a Holy Day of Obligation. Mass will be offered at 12:05 at the Cathedral.
Prepare for this special Solemnity by praying the Novena to the Assumption of the Blessed Virgin Mary, which can be found on the EWTN website: https://www.ewtn.com/Devotionals/novena/assumption_mary.htm