Thinking about the current situation in Alberta and Wildman 800's very useful post on hurricane readiness levels, I wondered if there was something equivalent for wild fires. Turns out there is - The National Fire Danger Readiness System:

Low (Green)—Fire starts are unlikely. Weather and fuel conditions will lead to slow fire spread, low intensity and relatively easy control with light mop-up. Controlled burns can usually be executed with reasonable safety.

Moderate (Blue)—Some wildfires may be expected. Expect moderate flame length and rate of spread. Control is usually not difficult and light to moderate mop-up can be expected. Although controlled burning can be done without creating a hazard, routine caution should be taken.

High (Yellow)—Wildfires are likely. Fires in heavy, continuous fuel such as mature grassland, weed fields and forest litter, will be difficult to control under windy conditions. Control through direct attack may be difficult but possible and mop-up will be required.
Outdoor burning should be restricted to early morning and late evening hours.

Lots more info at : https://www.nps.gov/fire/wildland-fire/learning-center/fire-in-depth/understanding-fire-danger.cfm

Very High (Orange)—Fires start easily from all causes and may spread faster than suppression resources can travel. Flame lengths will be long with high intensity, making control very difficult. Both suppression and mop-up will require an extended and very thorough effort. Outdoor burning is not recommended.

Extreme (Red)—Fires will start and spread rapidly. Every fire start has the potential to become large. Expect extreme, erratic fire behavior. NO OUTDOOR BURNING SHOULD TAKE PLACE IN AREAS WITH EXTREME FIRE DANGER.

What is lacking is advice on individual/family preps for the various levels, but this gang on ETS should be great at that.

Personally, somewhere around Orange, I would start loading up the vehicles and prepare to leave. As far as I am concerned, staying behind to fight fire is a good way to die. You also impede the professionals who will actually make a difference (in SoCal anyway)