Strong Wind Risk in the US: How FEMA Scores It and How to Prepare
Most wind damage in America has nothing to do with tornadoes. Straight-line thunderstorm winds — downbursts, gust fronts, and the long-lived windstorms called derechos — damage far more property in a typical year than tornadoes do, simply because they cover vastly more ground. The August 2020 Midwest derecho drove 100+ mph winds across 770 miles of Iowa and Illinois and caused roughly $11 billion in damage — more than most hurricanes. In the National Risk Index, strong wind (hazard code SWND) accounts for roughly $3.2 billion in national expected annual loss across 3,121 counties.
What counts as strong wind risk
The NRI’s strong wind hazard covers damaging straight-line winds outside tornadoes and hurricanes, which the index books separately. The main actors: downbursts (rain-cooled air slamming down from a storm and spreading out at 60–100+ mph), derechos (a chain of downbursts riding a fast-moving storm line for hundreds of miles), and severe gust fronts. Damage looks like a tornado’s weaker cousin spread over a huge area — trees down everywhere, roofs stripped, power out for days, grain bins and signs flattened.
The signature consequence is the power outage: straight-line wind is the leading cause of large blackouts in the US, because a single derecho can drop thousands of trees onto lines across several states at once.
How the NRI measures it
FEMA combines each county’s exposure (building value and population), annualized frequency of severe wind events from NOAA storm reports, and historic loss ratios into an Expected Annual Loss, scored 0–100 relative to all counties. As with the other storm hazards, the ranking rewards places where frequent severe wind crosses dense development.
Where the risk concentrates
The current top five is more geographically scattered than most hazards: Monmouth County, NJ leads (score 100, ~$91M expected annual loss, nearly 6 severe-wind events/year — the Jersey Shore’s exposure to both thunderstorm winds and nor’easter gradients), followed by Jackson County, OK, Orange and Polk Counties, FL (Orlando/Lakeland — Florida’s daily-thunderstorm capital), and Ocean County, NJ. The broader high-risk zones are the derecho corridor from the upper Midwest through the Ohio Valley, the southern Plains, and the mid-Atlantic coast.
How to read your county’s score
A high strong-wind score mostly forecasts trees on things and days without power, punctuated by occasional structural damage to roofs and outbuildings. The relevant questions: What is the condition of the large trees within falling distance of your house and service line? How long can your household run without grid power — especially refrigerated medication, well pumps, or medical equipment? Is your roof covering rated and in good condition (wind peels shingles at the edges first)?
What actually reduces the risk
- Manage the trees. Professional pruning of large trees near the house, and removal of dead or diseased ones, prevents the single most common severe-wind loss. After any big blow, re-inspect — partially failed limbs come down in the next storm.
- Backup power, sized honestly. A portable generator (run outdoors, far from openings — carbon monoxide kills more people after windstorms than the wind does) or battery station covering the fridge, phones, and medical gear turns a week-long outage into an inconvenience. Whole-home standby units make sense where outages are routine.
- Harden the roof edge: ring-shank nails or added fastening on sheathing during a re-roof, sealed roof deck, and rated shingles — the same upgrades that resist hurricanes resist derechos.
- Anchor the light stuff. Trampolines, patio umbrellas, and sheds become projectiles at 70 mph; carports and grain bins need engineered anchoring.
- Treat severe thunderstorm warnings seriously. “Destructive” (80+ mph) severe thunderstorm warnings now trigger phone alerts; that’s tornado-grade wind arriving in minutes — get inside, away from windows, and don’t wait to see it.