Cold Wave Risk in the US: How FEMA Scores It and How to Prepare
The most expensive cold-weather disaster in US history didn’t happen in Minnesota. It happened in Texas, in February 2021, when Winter Storm Uri held the state below freezing for days, collapsed the power grid, killed more than 200 people, and burst enough pipes to generate over $20 billion in insured losses. That event is the modern template for cold-wave risk: extreme cold is most dangerous where it is least expected. In the National Risk Index, cold waves (hazard code CWAV) account for roughly $9.9 billion in national expected annual loss — one of the largest hazards in the index — across 3,077 counties.
What counts as cold wave risk
The NRI’s cold wave hazard covers prolonged spells of dangerously low temperatures relative to what a region is built for — as distinct from winter weather (snow and blizzards) and ice storms, which the index tracks separately. Like heat, cold kills against a local baseline: -10°F is a normal Fargo commute and a statewide emergency in Houston, where homes have uninsulated pipes, heat pumps without backup strips, and no snow fleet exists.
The casualty mechanics are consistent: hypothermia among the homeless, elderly people in underheated homes, and people stranded in vehicles; carbon-monoxide poisoning from improvised indoor heating (generators, charcoal, ovens); and house fires from space heaters. The property loss is dominated by frozen and burst pipes — a single burst supply line can do tens of thousands of dollars of damage.
How the NRI measures it
FEMA combines each county’s exposure (population and building value), annualized cold-wave frequency from NOAA records, and historic loss ratios into an Expected Annual Loss scored 0–100 against all counties. Population-dense counties with real-but-occasional severe cold rank highest — the index is pricing people and property against how unusual the cold is, not against absolute temperature.
Where the risk concentrates
The top of the ranking pairs big-city exposure with serious cold: Cook County, IL (Chicago) leads with a score of 100 and a remarkable ~$700 million expected annual loss, followed by Milwaukee County, WI (~$177M). Then comes the Texas signature: Harris (Houston), Dallas, and Hidalgo (Rio Grande Valley) counties all sit in the national top five — enormous populations in housing never designed for hard freezes. High ratings blanket the Upper Midwest, Great Plains, and Northeast, but the Gulf South’s presence near the top is the risk map’s most important lesson.
How to read your county’s score
If you’re in the traditional cold belt, a high score mostly means the index is pricing your huge exposure — your housing and infrastructure are adapted, and preparation is routine. If you’re in a southern high-scoring county, take it as the Uri warning: your home probably has vulnerable plumbing, your heat probably depends on a grid that struggles in deep cold, and your community has thin cold-response capacity. The key questions: Where are your water pipes routed (attic and exterior-wall pipes are the burst risk)? What happens to your heat in a multi-day outage? Who do you know that lives alone and old?
What actually reduces the risk
- Protect the pipes: insulate exposed runs, seal crawl-space vents in freezes, drip faucets on exterior walls during hard cold, and — most important — know where your main shutoff is so a burst is a mess, not a flood. Leaving for the holidays? Keep heat at 55°F+ or shut off and drain.
- Heat safely or not at all. Space heaters need 3 feet of clearance and a hard surface; never heat with an oven, charcoal, or an indoor generator. CO detectors on every level are non-negotiable in outage-prone cold country.
- Have a no-grid heat plan: a safe backup source (wood stove, vented propane heater rated for indoor use, or a generator run outdoors), or a pre-decided warm destination. Layered clothing and closing off one room stretches whatever heat you have.
- Winterize the vehicle and carry a kit (blankets, water, snacks, phone charger, shovel) — stranding deaths cluster on rural highways in cold snaps.
- Check on vulnerable people daily during warnings — the same intervention that saves lives in heat waves saves them in cold.