Some regional parks, closed since Aug. 21 because of the wildfires, could reopen as early as Thursday, the East Bay Regional Park District said.

Lightning struck five parks last week and caused wildfires at Sunol, Ohlone Wilderness, Morgan Territory, Mission Peak, and Round Valley.

Depending on the air quality, which has improved in recent days, the district’s general manager hopes to reopen all sites not affected by the fires on Aug. 27.