Understanding fire in California requires familiarity with several key terms:

• Wildland Urban Interface (WUI): Areas where human development meets or intermingles with undeveloped wildland vegetation, increasing fire risk.

• Fire Severity Zone: A classification used to assess the likelihood and potential intensity of fires in specific areas. California designates zones as Moderate, High, or Very High Fire Hazard Severity Zones (FHSZ).

• Defensible Space: A buffer zone around structures where vegetation and flammable materials are managed to reduce fire spread and improve firefighter safety. California law requires specific defensible space measures (e.g., 100 feet around homes in high-risk areas).

• Prescribed Burn: A controlled fire intentionally set by professionals to reduce hazardous fuels, improve ecosystem health, and mitigate future wildfire risk.

• Firebreak: A gap in vegetation or other flammable material designed to slow or stop the spread of fire. Firebreaks can be natural (e.g., rivers) or human-made (e.g., cleared land, trails, farmland--even freeways).

• Red Flag Warning: A weather alert issued by the National Weather Service indicating extreme fire conditions, such as strong winds, low humidity, and dry fuels.

• Santa Ana Winds: Strong, dry winds that originate inland and move toward coastal Southern California, increasing wildfire risk by rapidly spreading flames. Similar conditions exist in Northern California, known as Diablo Winds.

• Megafire: A wildfire that burns more than 100,000 acres, often causing extensive damage and lasting for weeks or months.

• Fire-adapted Ecosystem: An ecosystem that has evolved to withstand and even benefit from periodic fire. Many California plant species rely on fire for regeneration.

• Ember Storm: A phenomenon in which wind-driven embers travel ahead of the fire front, igniting spot fires and causing rapid fire spread, especially in WUI areas. The Eaton and Palisades fires stemmed from an ember storm.