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.

Californians in the greater Los Angeles area have been on edge due to high winds and dry conditions. The Palisades and Eaton fires have killed at least 25 and destroyed thousands of homes.

We've seen reports about Los Angeles County being under "fire weather watch" and "red flag warning." What is the difference?

The most serious red flag fire weather warning has been issued by the NWS for swaths of L.A. and Ventura counties starting before dawn Tuesday.

"If fire ignition occurs, conditions are favorable for very rapid fire spread and extreme fire behavior," the NWS warns.

As firefighters struggle to gain control of massive and deadly wildfires that are raging across parts of the Los Angeles area, the region is once again bracing for the potential of new fires and for current ones to intensify as a new storm system heads for the state.

A red flag warning has been issued through Wednesday in Southern California because of potentially dangerous fire conditions.

A red flag warning for Wednesday has been issued for Southern California as concerns about the fast-growing wildfires increasing.

Red flag warnings tell other agencies, like fire and transportation departments, that it's time to staff up and prepare to respond to fast-moving fires. But they're also intended to put the public on high alert.

As last week’s infernos still blaze in Los Angeles, the National Weather Service issued a Red Flag fire warning for portions of San Luis Obispo County on Monday.

The National Weather Service has issued a Red Flag Warning for most of San Diego County amid another round of Santa Ana winds.

The latest red flag warning includes the Inland Empire and Orange County, as well as the already ravaged Los Angeles area.