"The Apple Fire burning in parts of Riverside and San Bernardino counties has grown to at least 20,516 acres and is 5% contained, the California Interagency Incident Management Team said.

There are several factors coming together to create major hurdles for firefighters who are battling the blaze. Terrain is the biggest, said Lisa Cox, the fire information officer for the San Bernardino National Forest.

'We've got extremely steep, rugged terrain,' Cox said. 'We have many different drainages that are all kind of intersecting together and that creates these funneling effects of different wind patterns and creates more erratic fire behavior.'"

Alta Spells reports for CNN August 3, 2020. [2]