Wildfire Risk in California Mapped

Oct 9 · 3 min read

Today we release Defensible, a statewide view of wildfire risk…

Building Level Wildfire Risk in the heart of Silicon Valley

As Northern California braces for widespread planned power outages and the closure of several key transportation routes, millions are adjusting to a new reality of fire season. The horrible wildfires in recent years have claimed dozens of lives and cost billions of dollars in residential and commercial real estate loss. Whole towns and regions have been affected, and those that remain in high risk areas have seen their insurance rates rise precipitously. In some instances, insurers have dropped coverage completely. Fire related issues have caused the largest public utility in Northern California to declare bankruptcy.

The decisions to cut power or even to ensure a particular property are made partly via maps that the general public has never seen. More troubling, there isn’t a plan to educate people about what these maps tell us. We wonder if public access to a map like this will help people become more aware of their risk, safeguard their properties, and even save lives.

Oakland Hills are a known quantity (1991 Wildfire event)

We began to work on a project to liberate these maps and make the information available to people who have the most at stake.

The maps are meant to be simple: every building is ranked on a scale from 1–100 based upon its relative risk to wildfire in the state. To make this happen we used maps from the US Forest Service Fire Lab and the USGS version of the same thing (called ‘Landfire’). This data gives us an understanding of what the existing fuels are in approximately 1km radius from every building (made possible by the amazing bing building footprint data).

Santa Ana Winds often set Metropolitan Los Angeles Metro Ablaze in the fall

The result is a map that we hope is as useful as it is simple. Type in an address or a place and the map shows any property’s relative risk . Understanding and mapping risk can be tricky, but overall it is better to have a map that shows people similar data that insurers are using to set rates

We hope this is just a start. There’s much more that could go into accurately measuring a building’s current risk. In the coming months we hope to be adding to this map, perhaps by extending to other states, by adding variables to the risk model, by helping homeowners better understand what actions they can take now and during a fire. Thank you for reading and if you have any feedback don’t hesitate to email us.

Disclaimer: this map is an approximation of risk. Actual events can and do affect buildings in the lowest risk categories.


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Preventative Medicine for Wildfires

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