Vegetation - Vegetation is "fuel" to a wildfire and it changes over time. Fire hazard considers the potential vegetation over a 50 year time horizon.
Topography - Fire burns faster on steep slopes.
Weather - Fire burns faster and with more intensity when air temperature is high, relative humidity is low, and winds are strong.
Crown fire potential - Under extreme conditions, fires burn up into trees and tall brush.
Ember production and movement - Fire brands are blown ahead of the main fire, spreading the fire and getting into buildings and igniting.
Likelihood of an area burning - over a 30 - 50 year time period.
Government Code section 51181 requires CAL FIRE to periodically review the very high fire hazard severity zone areas and make updated recommendations as needed.
Utilizing the latest and best fire modeling methods CAL FIRE has reevaluated wild-fire hazards and identified very high fire hazard severity zones in the state.
Very high fire hazard severity zones were originally established in 1996 (AB 337 – Bates Bill) and adopted by ordinance into the San Clemente Municipal Code, Chapter 8.22 – VERY HIGH FIRE HAZARD SEVERITY ZONES.
Local jurisdictions are required to designate the updated very high fire hazard zones within 120 days after receiving recommendations from CAL FIRE.
Orange County Very High Fire Hazard Severity Zone Map (Oct 2011)