humidity

“Tuesday and Wednesday, we have very low humidity and some winds out there,” Walbrun said.

Winds could reach up to 35 or 45 mph on some high peaks Tuesday and Wednesday as humidity is expected to drop, creating some more challenging conditions, said Ryan Walbrun, a National Weather Service meteorologist assigned to the Mountain fire.

The Thomas fire, which destroyed over 1,000 structures and burned more than 281,000 acres in Santa Barbara and Ventura counties, also grew under similar circumstances as the Mountain and Woolsey fires: with low humidity, active Santa Ana winds and lots of dry brush in a mixed wildland and urban environment.

This means extreme precipitation "will be more extreme" and, under some global warming scenarios, heat and humidity could mean some parts of the country "would not be liveable", he says.

Light winds coming from the ocean and favorable humidity levels Sunday helped authorities in the effort to contain the fire, which started Wednesday morning amid an extreme Santa Ana wind event.