'Bolts From The Blue' Are A Thunderstorm Danger

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Summer's widespread thunderstorm activity increases the threat of dangerous lightning strikes, including where it's not raining and we see so-called "bolts from the blue."

Thunderstorms pack a lightning danger for miles. L​ightning often strikes more than 3 miles from where the core of a thunderstorm is located, according to NOAA. Occasionally, strikes can occur even farther away at distances of 10 to 15 miles.

The strikes where it's not pouring rain are sometimes called "bolts from the blue" – named because these lightning bolts in some cases appear to come from a clear sky, as shown in the image below from Florida a few years ago.

Radar shows how lightning can strike far from a thunderstorm's core. A​nother way to illustrate these rogue strikes is by examining radar and lightning data together.

T​he radar image below centered to the north of New Orleans on the evening of June 4, 2023, showed four separate strikes north of a storm's heavy rain core (yellow, orange, red shadings). Little, if any, rain was falling near those strikes.

If you hear thunder, it's time to shelter. The best way to stay out of danger from these distant lightning strikes is to be weather-aware and use common sense.

If the sky is darkening and particularly if you hear thunder, you're in danger. Head indoors or into a vehicle immediately until the storm passes.

M​ore proof of why you should take action immediately when hearing thunder is shown in the graphic below.

As you would expect, the lightning risk is highest when a storm is overhead. However, the number of lightning casualties is just as high for some of the time when a storm is approaching or after it has departed.

T​hat's because many people wait too long to take shelter and then leave that shelter earlier than they should, according to NOAA.

​Lightning contributes to weather-related fatalities every year. An average of 22 people per year in the U.S. were killed by lightning from 2013 to 2022. Hundreds more are injured, NOAA says.

I​f you have outdoor plans, it's important to stay up-to-date on the forecast and current conditions. You should also make sure you have access to a nearby shelter if any storms are in the forecast.

Some weather apps – such as The Weather Channel app – will send you a lightning alert if a strike occurs nearby.

Chris Dolce has been a senior meteorologist with weather.com for over 10 years after beginning his career with The Weather Channel in the early 2000s.

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