City of Tucson issued the following announcement on Sept. 9.
Sentinel Peak Park ('A' Mountain) will be closed to all traffic from Sept. 13-27. Crews will be working to repair the rock structure of the "A" on the mountain. During this time, no vehicular, bicycle, or pedestrian traffic will be allowed past the lower parking lot. Once the mountain reopens on Tuesday, Sept. 28, the City of Tucson will be piloting new operating hours. The park hours remain open from sunrise to sunset. There will be no vehicle access on Mondays. Vehicles can access the mountain from 2 p.m.-sunset, Tuesdays through Thursdays, and from 11 a.m.-sunset, Fridays through Sundays.
Original source can be found here.