Wildfire Risk in the US: How FEMA Scores It and How to Prepare

Written by Dvir · Data: FEMA National Risk Index v1.20 · Updated August 4, 2026

Wildfire has gone from a regional concern to one of the defining American disaster risks in a single generation. The deadliest US fire in a century (Camp Fire, Paradise, CA, 2018), the costliest urban firestorms (Los Angeles, January 2025), and the Maui fire of 2023 all share one anatomy: wind-driven fire reaching neighborhoods built into flammable landscapes. In the National Risk Index, wildfire (hazard code WFIR) carries roughly $3.9 billion in national expected annual loss — with measurable risk in all 3,143 counties, but extreme concentration in a handful of them.

What counts as wildfire risk

The NRI’s wildfire hazard covers uncontrolled fires in vegetation — forest, brush, and grass — including those that transition into communities. The decisive concept is the wildland-urban interface (WUI): the zone where homes intermingle with burnable vegetation. Fire behavior in the WUI is dominated by embers, which can travel a mile or more ahead of a fire front and ignite homes through vents, gutters full of needles, and wooden fences attached to the house. Most homes lost in wildfires are ignited by embers, not by a wall of flame.

Fire needs fuel, dryness, and wind. That is why the worst events cluster in wind seasons — Santa Ana and Diablo winds in California, chinook winds along the Front Range — and in drought years, when fuels reach single-digit moisture.

How the NRI measures it

FEMA builds each county’s wildfire Expected Annual Loss from exposure (building value, population, and agriculture in burnable areas, using US Forest Service wildfire hazard potential data), annualized fire frequency, and the historic loss ratio of fire events. The result is scored 0–100 against all other counties.

Because exposure drives the math, the ranking rewards places where expensive housing meets flammable terrain — not necessarily where the most acres burn. Millions of acres burn in sparsely populated rangeland every year with modest dollar losses.

Where the risk concentrates

Southern California owns the top of the national ranking. Riverside County and San Diego County lead with wildfire scores of 100 and expected annual losses around $347M and $430M respectively, followed by Los Angeles and San Bernardino counties (~$155M and $146M). The pattern extends through the Sierra foothills, and high ratings continue through Nevada (Elko County is a top-five county nationally), Arizona, Colorado’s Front Range, Oregon, Washington, and the Texas Hill Country. Fast-growing WUI development in the Mountain West is pushing risk up steadily, and events like the 2021 Marshall Fire in suburban Boulder County, Colorado — a December grass fire that destroyed over 1,000 homes — show the risk is no longer confined to forested mountains.

How to read your county’s score

A Very High county score means substantial value sits where fire can reach it — but wildfire is the most parcel-specific hazard in the index. Within the same county, a home in a stucco subdivision surrounded by irrigated lawns and a home on a brushy canyon rim face utterly different odds. Use the county score as a prompt to check your specific parcel: state fire-hazard severity maps (California’s CAL FIRE maps are the model), and whether your insurer is repricing or non-renewing in your area — insurance availability has become a leading indicator of fire risk.

What actually reduces the risk

Research from IBHS and post-fire damage surveys is unusually clear on what saves homes:

  • Harden against embers first. Ember-resistant vents (1/8” metal mesh), clean gutters, and no combustible mulch or vegetation within 5 feet of the structure (Zone 0) matter more than anything else. California now mandates ember-resistant Zone 0 for new WUI construction.
  • Roof and siding class. A Class A roof (asphalt shingle, metal, tile with bird-stops) is the single most important structural feature. Wood-shake roofs are catastrophic.
  • Defensible space, 0–100 feet. Thin vegetation, limb trees, break up fuel continuity. A wooden fence touching the house is a fuse — replace the last 5 feet with metal.
  • Plan to leave early. Fatalities cluster in late evacuations. Know two ways out, sign up for county alerts, and treat Red Flag Warning days as pre-positioning days.
  • Insurance before the smoke. Binding moratoriums freeze new coverage once a fire ignites nearby. Review dwelling limits annually; rebuild costs after big fires routinely exceed pre-fire estimates.

The fires that changed the calculus

The Great Fire of 1910 (“the Big Burn”) swept roughly three million acres of Idaho and Montana in two days and killed dozens of firefighters. It cemented total suppression as US forest policy for most of a century — a decision that protected communities in the short run and loaded the landscape with unburned fuel in the long run. Nearly every modern conversation about prescribed fire is an argument with 1910.

The Oakland Hills firestorm (1991) burned into a dense East Bay neighborhood, destroyed thousands of homes and apartments in a single afternoon, and killed 25 people. It was the first modern American event to demonstrate that a wildfire could behave as an urban conflagration, spreading house-to-house independent of the vegetation that started it.

The Camp Fire (2018) destroyed the town of Paradise, California and killed 85 people — the deadliest US wildfire in a century. Post-fire analysis found the fire moved faster than the evacuation could, that a large share of ignitions came from embers landing on and in structures, and that the difference between surviving and destroyed homes frequently came down to details measured in inches: vent screening, gutter debris, a wooden fence attached to siding.

The Marshall Fire (December 2021) burned more than a thousand homes in suburban Boulder County, Colorado — in winter, in grass, in subdivisions with no forest anywhere near them. It ended the assumption that wildfire risk requires trees.

The Lahaina fire (August 2023) killed roughly 100 people on Maui when a wind-driven grass fire entered a dense historic town, and the January 2025 Los Angeles firestorms produced some of the costliest urban fire losses in American history. Both followed the same script: extreme wind, cured fuels, ignition near a community, and fire spread faster than warning and evacuation systems could keep up.

The through-line: the modern disaster is not a forest fire. It is a wind-driven ember storm entering a neighborhood, where houses become the fuel.

Season, wind, and where the losses concentrate

Wildfire has a season, but the destructive season is defined by wind rather than by heat.

  • Spring (March–May), southern Plains and Southeast. Cured grass before green-up, low humidity, and strong frontal winds. Texas, Oklahoma, and Kansas see enormous grass fires in this window.
  • Summer (June–September), Interior West and Northwest. The classic large-forest-fire season, driven by drought, lightning ignitions, and long-duration heat.
  • Autumn (September–December), California and the Front Range. The most destructive period in the country. Offshore wind events — Santa Ana winds in southern California, Diablo winds in the north, downslope chinook winds along Colorado’s Front Range — arrive when fuels are at their driest, before the first significant rain. Nearly all of California’s most destructive fires have occurred under these conditions.
  • Winter, in an increasing number of places. Marshall (December) and Lahaina (August, but in a normally wet climate) both show that fuel dryness plus wind, not the calendar, is what matters.

In the National Risk Index, the highest wildfire expected annual losses concentrate where expensive housing meets flammable terrain: southern California’s canyon and foothill communities, the Sierra foothills, Colorado’s Front Range, the Wasatch Front, central Texas, the eastern Cascades and the Rogue and Willamette valleys of Oregon, and inland Washington. Millions of acres burn every year on rangeland with modest dollar losses, so the ranking is a map of exposure, not of acres burned.

Home hardening, in the order that matters

Post-fire damage surveys have converged on a clear hierarchy. Embers cause most home ignitions, so the work is about denying embers a place to land and burn.

  • Zone 0 — the first five feet. This is now understood to be the single most important zone. Nothing combustible within five feet of the wall: no bark mulch, no shrubs against siding, no woodpile, no plastic trash bins, no stored fuel or cushions. Gravel, stone, or bare soil instead. California has moved to require ember-resistant Zone 0 for new construction in high-severity zones.
  • Vents. Ember-resistant vents, or 1/8-inch metal mesh screening at minimum, on every attic, soffit, crawlspace, and dryer vent. Embers entering an attic ignite the house from inside, where nobody can put it out.
  • Roof class and condition. A Class A roof — asphalt shingle, metal, concrete or clay tile with bird-stops at the eaves — is essential. Wood shake roofs are catastrophic. Just as important: keep the roof, valleys, and gutters clear of needles and leaves, which is where embers find fuel.
  • Fences and decks. A wooden fence attached to the house is a fuse leading directly to the siding; replace the last five feet with metal or masonry. Decks need noncombustible or ember-resistant decking, sealed gaps, and nothing stored underneath.
  • Windows. Dual-pane, with at least one tempered pane, resists the radiant heat that breaks single-pane glass and lets fire inside.
  • Defensible space, 5–30 and 30–100 feet. Break up fuel continuity: thin and space shrubs, limb trees up from the ground, keep grass short, and separate tree canopies from the roof. The goal is not a moonscape; it is to prevent flame reaching the structure and to give firefighters a place to stand.
  • Address the neighborhood, not just the parcel. In dense subdivisions, house-to-house radiant ignition dominates. Community programs — Firewise USA, the IBHS Wildfire Prepared Neighborhood designation — exist because your neighbor’s untreated fence is your problem.
  • Water and access. A long hose that reaches all sides, a driveway wide enough for an engine, and clearly visible address numbers matter more than most people expect.

Insurance, availability, and documentation

Wildfire is the hazard where the insurance market itself has become a risk signal.

  • Fire is covered by standard homeowners policies — the problem is getting and keeping one. Insurers have non-renewed policies and withdrawn from high-hazard areas in California, Colorado, and elsewhere. If your insurer leaves, the state’s insurer of last resort (California’s FAIR Plan and its equivalents) provides limited fire-only coverage that usually needs a wraparound policy for liability and water damage.
  • Watch the deductible and the limits, not just the premium. Total losses in wildfire are common, and post-fire construction cost spikes are extreme when hundreds of homes rebuild at once. Extended replacement cost (typically 25–50% above the dwelling limit) and ordinance or law coverage are what close the gap between your limit and the actual rebuild bill.
  • Binding moratoriums. Once a fire is burning nearby, insurers stop writing and changing policies in the area. Every adjustment has to be made in advance.
  • Mitigation discounts are real. California requires insurers to recognize “Safer from Wildfires” mitigation, and IBHS Wildfire Prepared Home certification earns discounts with participating carriers. Keep receipts and photos of the work.
  • Contents claims are won with inventory. After a total loss you will be asked to list what you owned. Video every room, open every closet and drawer, and store the file in the cloud. This is the single most valuable hour of preparation for this hazard.
  • Smoke damage counts. Homes that do not burn frequently sustain expensive smoke and ash contamination, which is covered but often under-claimed.

Before, during, and after

Before. Check your parcel’s hazard on your state’s fire-severity maps and on Wildfire Risk to Communities, not just your county’s score. Sign up for county emergency alerts — wildfire evacuation orders often come through local systems rather than federal ones — and identify two ways out of your neighborhood, because the primary route is frequently the one that closes. Treat Red Flag Warning days as pre-positioning days: park facing out, keep the tank full, put the go-bag by the door. Keep documents, medications, hard drives, and irreplaceable items in one grab-and-go container.

During. Leave early. Fatalities cluster overwhelmingly in late evacuations, in vehicles, on roads that fill with smoke and traffic. Do not wait for a mandatory order if conditions look wrong and you have a way out. If you have time as you leave, close all windows and doors (unlocked for firefighters), shut interior doors, move furniture away from windows, turn off gas at the meter if instructed, and leave exterior lights on so the house is visible in smoke. Wear cotton or wool rather than synthetics, long sleeves, and boots.

After. Do not return until the area is cleared — hazards include burned-out root holes, unstable trees, live wires, and hot ash that can reignite. Wildfire ash contains heavy metals and asbestos from burned structures: wear an N95 or better, gloves, and closed shoes, and do not let children play in it. Photograph everything before touching anything. Post-fire debris flows are a serious secondary hazard for the first several rainy seasons after a burn — a modest rainstorm on a burn scar can produce a destructive mudflow miles downstream, and it is a flood claim, not a fire claim.

Sources

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