The Bobcat Fire started deep within the Angeles National Forest (LA Times) in the San Gabriel Mountains. It has since exploded and have become a major concern to the cities at the foothills (Arcadia, Duarte, Monrovia, Sierra Madre) while also now threatening Mt Wilson Observatory (LAist). What does this immediately mean? Based on the Arcadia news, Chantry Flats and the Big Santa Anita Canyon hike to Sturtevant Falls and Hermit Falls are probably burned. It looks like the Monrovia Falls hike is also burned as well.
The biggest concern will be Mt Wilson Observatory and the residential communities at the base of the mountains. Evacuation orders and warnings have been issued at least in Arcadia. Stay safe