The most destructive wildfires in Los Angeles history Thursday have burned more than 54 square miles of land, destroyed thousands of structures and killed at least five people.

Red flag criteria is generally when relative humidity is at 15% or less, combined with sustained winds and/or gusts of 25 mph or greater. Both of these conditions must occur simultaneously for at least 3 hours in a 12 hour period, according to the NWS.

A short reprieve in the strong destructive winds has granted firefighters an opportunity to curb the spread of the deadly Eaton Fire near Pasadena.