MAP: Do You Live in a High-Risk Fire Zone?


ust about anywhere you live in California, you may face the threat of wildfires. But the danger varies dramatically depending on exactly where you live.

Currently, Californians can assess their risk using a set of maps released in 2007 by Cal Fire's Office of the State Fire Marshal.

Over the next year, that's expected to change. The agency is expected to release new draft maps to test this winter that take new risk factors into account, according to Dave Sapsis, a Cal Fire researcher who specializes in mapping and research models.

Lisa Pickoff-White/KQED

The current maps show the probability of wildfire in a given area by assessing vegetation, fire history and topography, since steeper slopes have higher fire risk. The hazard is ranked in three categories: moderate, high and very high. There are also two other categories: "non-wildland, non-urban" and "urban unzoned."

Living With Fire

"How likely is the fire? And what is the nature of the fire?" Sapsis says. "The model is basically trying to describe areas and their likelihood for a structure to ignite,"

Sapsis says it's important to remember that the Cal Fire-defined risk zones are showing only a probability.

"Estimating a burn probability is an estimate. It's like estimating the weather. We do the best we can based on the tools we have," he says.

And, as recent fires have tragically demonstrated, living outside a higher-risk zone doesn't mean that you're safe.

Extreme winds drove much of the damage in Paradise during last November's Camp Fire and in the North Bay during the October 2017 fire siege, and current fire maps don't take that factor into account.

New Maps to Assess Weather and Development

Sapsis says that fire modeling technology is improving all the time, and that the new models Cal Fire is testing are taking into account dry, windy weather.

"We're just now getting the capacity to estimate at a realistic scale what these areas, footprints, if you will, of these dry windy events are ... and what the magnitudes of these events are," Sapsis says.

Those kinds of weather conditions are tricky to map, Sapsis says, because you want to take into account those very destructive types of fires, but also need to consider a longer, 50-year period.

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.

The new maps are meant to show "where fires could go," not where they could start, Sapsis says.

For instance, development patterns can change how fire spreads. In urban areas, fires can move quickly through dense neighborhoods where homes are tightly spaced.

"You don't want to zone that house based on what's there, but what could potentially be there," Sapsis says.

Cal Fire hopes to start testing its new draft maps this winter. The agency expects to release official maps next summer for "state responsibility areas" -- the parts of California areas that it's responsible for protecting. After that, Cal Fire will work with local governments to develop new maps for those areas, too.

Note: KQED has simplified these maps for online display. For more detail, please see Cal Fire's official county maps for both state and local responsibility areas.