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 particularly dangerous situation red flag warning is in place from noon Monday to 10 a.m. PT Tuesday for a large portion of Ventura and Los Angeles counties.