Lightning Risk in the US: How FEMA Scores It and How to Prepare
Lightning strikes the United States about 25 million times a year — it is the most frequent hazard in the entire National Risk Index, with top counties logging 75–100 strike events annually. Yet it kills fewer Americans each year (recently around 10–20) than almost any hazard on this site, a public-safety success story built on one slogan. The remaining risk is stubbornly specific: people outdoors who didn’t go in, and property losses from fires, surges, and fried electronics. The NRI books roughly $1.6 billion in national expected annual loss to lightning (hazard code LTNG) across all 3,143 counties.
What counts as lightning risk
The NRI’s lightning hazard covers cloud-to-ground strikes and their direct consequences: casualties, structure fires, and damage to electrical systems and equipment. A bolt carries around 300 million volts and heats its channel to five times the sun’s surface temperature; what it touches, it ignites or destroys. Most victims are not struck directly — ground current radiating from a nearby strike, side flashes from trees, and conduction through wiring and plumbing account for most casualties, which is why “under a tree” and “on a corded phone” are classic case reports.
The behavioral profile is well documented: about 80% of US lightning victims are male, most are struck during leisure activities (fishing is the leading single activity), and the fatal window is disproportionately before and after the rain — when the storm seems far enough away.
How the NRI measures it
FEMA combines each county’s exposure (population and building value), annualized strike-event frequency from national lightning-detection network data, and historic loss ratios into an Expected Annual Loss scored 0–100 against all counties. Frequency dominates: the ranking traces America’s thunderstorm climatology across its biggest cities.
Where the risk concentrates
Florida is the US lightning capital, and the ranking shows it: Broward County (Fort Lauderdale) leads with a score of 100 and ~99 strike events/year, with Miami-Dade close behind (~98 events/year). The rest of the top five spans the thunderstorm belt: Honolulu County, HI (~77 events/year across a large exposed population), Harris County, TX (Houston, ~75/year), and El Paso County, TX (the monsoon-season desert Southwest). The broader high-frequency zone runs from Florida up the Gulf Coast and across the Southeast — Tampa Bay’s “Lightning Alley” sees more strikes than anywhere else in the country.
How to read your county’s score
Lightning risk is behavioral more than geographic: a high county score means more storm-hours per year during which the same universal rules apply. If you or your family spend serious time outdoors — golf, boating, fishing, youth sports, landscaping, roofing — frequency translates directly into personal exposure. For property, high-frequency counties justify surge protection and, for tall or isolated structures, engineered protection systems.
What actually reduces the risk
- “When thunder roars, go indoors.” If you can hear thunder, the storm is within strike range (bolts routinely travel 10+ miles). Wait 30 minutes after the last thunder before resuming. This one rule is why US lightning deaths fell from hundreds a year to a dozen.
- Safe shelter means a substantial building or a hard-topped vehicle. Pavilions, dugouts, tents, and golf carts are not shelter. Indoors, stay off corded devices and out of showers during the storm — wiring and plumbing conduct.
- Coaches and organizers: have a lightning plan. Youth sports are a recurring casualty setting; designate shelter, assign a weather watcher, use a lightning app, and don’t restart early.
- Protect the electronics: whole-house surge protection at the panel (now required in new construction by NEC 2020) plus point-of-use protectors for valuable equipment. Unplugging ahead of storms is still the only 100% protection.
- Lightning rods work. A professionally installed lightning protection system (UL 96A / NFPA 780) doesn’t attract lightning; it gives a strike a safe path to ground. Worth it for tall, isolated, or high-value structures — and for barns; livestock losses are a steady rural cost.
- If someone is struck: call 911 and start CPR immediately. Victims carry no charge, and prompt CPR has an excellent save rate — cardiac arrest is the mechanism of death, and it’s reversible.