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.

The National Weather Service on Wednesday extended the wildfire warning through the end of the week for much of East County.

A Red Flag Warning has been extended for portions of San Diego County ahead of another bout of strong Santa Ana winds.