What Is The Phenomenon 'Bolt From The Blue'?

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W​e often see lightning strike as rain pours down, but did you know it can be dangerous even in sunny skies from a so-called "bolt from the blue"?

Recent radar shows how lightning can strike far from a thunderstorm's core. T​he radar image below is from the night of April 29 in central Arkansas. It shows a lightning strike, or "bolt from the blue," about 12 miles away from the thunderstorm that produced it, according to the National Weather Service in Little Rock.

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T​his illustrates why we always say that if you hear thunder, you're in danger and should seek shelter immediately even if it's not raining where you are.

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

The "bolt from the blue" name for this phenomenon is because in some cases, the lightning strike appears to come from a clear, sometimes blue sky.

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​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.

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

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.

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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.