Wednesday’s critical conditions are due to the effects of moderate to locally strong Santa Ana winds coupled with very low humidity, BBC Weather forecaster Sarah Keith-Lucas said.
Winds are expected to peak again at 03:00 local time (11:00 GMT) for twelve hours, according to the local office of the National Weather Service (NWS). Wind can reach 50mph (80km/h).
Compared to last week’s conditions, winds were “weaker but still strong”, the NWS warned.
Because of that, the area northwest of Los Angeles — including Simi Valley and Thousand Oaks — has been deemed particularly dangerous.
But an improvement in the situation is expected later on Thursday and Friday. Despite the change in winds, no rain is forecast for at least the next week, added BBC forecaster Sarah Keith-Lucas. And the Santa Ana winds blamed for fueling the fire could develop again as early as Sunday.
The fire chief for the city of Pasadena echoed the need for precipitation.
There has been “no real rain in southern California” for more than 250 days, Chad Augustin told BBC Radio 4’s Today programme.
On Wednesday, his firefighters will “keep ready to make sure we hold our containment line and we don’t burn the structure again”, Mr Augustin added.
