Strong Santa Ana Winds. Humidity in single digits. Lots of scrub brush for fuel.
Little sparks or fires that would normally die out can turn into an inferno in these conditions. Road flares set off the Canyon 1 Fire in OC about a month ago.
Single digit humidity, wow. We think humidity is low here in winter when it gets below 40%. But then, compared to our summer it is. I’d imagine there’s quite a problem with static discharge, here you can get a slight shock touching anything metal just from walking across the room.