Wildfire risk is widespread throughout California, but it varies dramatically according to where you live.
So, in the hope of better preparedness, Cal Fire released a set of maps in 2007 that purport to show where the hazard is highest.
Some say the Bay Area's recent Wine Country fires illustrate the shortcomings of these maps, which designate where tougher building codes are required. Many of the neighborhoods that burned to the ground were outside the hazard zones.
See maps for the entire state here.
What These Maps Show
The maps show the probability of wildfire in a given area by taking a number of factors into account: vegetation, fire history and topography (since steeper slopes have higher fire risk).
The hazard zones come in three categories: moderate, high and very high.
“These are big-picture maps that apply to building codes,” says Daniel Berlant, assistant deputy director of Cal Fire.
New construction in these zones must meet tougher standards for fire-resistance of roofs, attic venting, windows and decks.
Cal Fire officials also point out -- and as the North Bay fires tragically demonstrated -- that living outside of these zones doesn’t mean that you’re safe.
“No matter where you live in California, you are at risk for wildfires,” says Berlant.
What These Maps Don’t Show
In the North Bay, extreme winds drove much of the devastation, but the state’s fire hazard maps don’t take the most extreme weather conditions into account.
“That’s a big gap in their effectiveness,” says Max Moritz, a fire expert with the University of California Cooperative Extension. “The weather conditions [on which the maps are based] aren’t all that bad. So, when you do look at your own rating, you’ll miss a lot of local detail.”
The fires also moved quickly through dense neighborhoods where homes were tightly spaced. But the maps don’t account for granular development patterns.
Fire “hazard” is a measure of how a fire will behave, based on the physical conditions. But the risk, or how much damage a fire can do, depends on the built environment.
In addition, the fire hazard maps don’t show the full level of risk within cities and local jurisdictions.
Three risk categories are mapped within “state responsibility areas,” where Cal Fire is responsible for wildfire control.
But within “local responsibility areas,” where cities are in charge of zoning and firefighting, only the “very high” hazard category is mapped.
The other two categories, “high” and “moderate,” are not required to be mapped within city boundaries by the state legislation that created the hazard mapping program, which means the fire building codes don’t apply there. However, they can be seen on the draft maps for each county.
Some cities have taken on their own risk assessment for fires or mandated stronger building codes, but state law only requires stricter building codes within the “very high” category of local jurisdictions.
Map Update Underway
Officials at Cal Fire say the fire hazard maps are in the process of being updated, now that they’re a decade old.
“They’re not all that current and there have been a lot of advances in fire hazard mapping,” says Moritz.
Cal Fire officials wouldn’t provide specific details about what the new maps will show, but say they’re looking at how to improve them.
“After these fires, we’re going to take a good review of what we’ve done in the past and look at whether are there other factors we should take it into account,” says Berlant.