Why Is Lightning Dangerous?

About 10,000 People Are Killed by It Every Year

Lightning , Tornado Alley , USA
Samuel D. Barricklow/Stone/Getty Images

Getting hit by lightning seems like an improbably unlucky event, but it happens more often than we might think.

Lightning Strikes Are Common

Worldwide, 16 million lightning storms occur every year—2,000 of those storms are happening simultaneously at any given moment—and it's more than just a spectacular natural light show.

Every year, lightning kills roughly 10,000 people around the world. In the U.S., on average 90 deaths are reported. Injuries are even more common, at about 100,000 globally and 400 in the U.S. Lightning strikes are not distributed evenly. Hot spots include the Midwestern and southeast United States, Central America, northern regions of South America, sub-Saharan Africa, Madagascar, and Southeast Asia. Basically, regions that experience hot and humid weather tend to see more thunderstorm activity.

What makes lightning so dangerous, and how does it compare with other weather hazards?

They're Underrated and Unpredictable

Lightning is the world's most underrated weather hazard. It's also the most unpredictable.

When it comes to lethal weather, lightning is hard to beat. On average only floods kill more people than lightning. In the United States (and most other places), lightning routinely kills more people every year than tornadoes or hurricanes. Other weather hazards, such as hailstorms and windstorms, aren't even in the running.

One reason lightning is so dangerous is that it's hard to know just when and where it is likely to strike—or how it will behave when it does.

"Lightning is the first thunderstorm hazard to arrive and the last to leave," according to the U.S. National Weather Service. Lightning can actually strike outside the storm that produced it. Although most lightning will strike within 10 miles of its parent thunderstorm, it can strike much farther away. On rare occasions, lightning-detection equipment has recorded lightning striking up to 50 miles away from the thunderstorm.

Lightning Makes Every Thunderstorm a Potential Killer

Another reason lightning is so dangerous is because of the destructive power it carries. The average lightning bolt carries about 30,000 amps of charge, has 100 million volts of electric potential, and is hot, hot, hot at about 50,000 degrees Fahrenheit.

Add up all of these factors, and it's pretty clear that lightning makes every thunderstorm a potential killer, whether the storm produces one lightning bolt or 10,000. In addition to the direct electrical dangers, lightning can create unstable and dangerous conditions: they start building fires, create power outages, and send wood shards flying from hit trees. Overall in the United States, about 20% of wildfires are caused by lightning, but that proportion climbs above 60% in the Great Basin region. The situation is worsened by regional droughts.

Not Restricted to Thunderstorms

To make matters worse, lightning isn't restricted to thunderstorms. Although you can't have a thunderstorm without lightning—thunder is the sound that lightning makes—you can have lightning without a thunderstorm.

Lightning has been seen during volcanic eruptions and extremely intense forest fires. It has also occurred during hurricanes and heavy snowstorms (popularly called thundersnow). Lightning has even been seen during surface nuclear detonations.

Lightning is unpredictable in other ways, too. Lightning can occur from cloud-to-cloud, cloud-to-ground, cloud-to-air, or within a cloud. And lightning can take many different forms, from streak lightning that appears as a single arc to ball lightning, which manifests as a glowing ball that floats in the air, may move slow or fast or remain in one place, and often explodes with a loud bang.


Edited by Frederic Beaudry.