Two massive lightning bolts recently broke shocking new records. 

A bolt stretching nearly 800 kilometres (500 miles) across three states now holds the record for the longest lightning flash.  

On 7 February 2022, the World Meteorological Organization announced that a single bolt on 29 April 2020 stretched over 767 kilometres (477 miles) across Texas, Louisiana, and Mississippi. This incredible length is equivalent to the distance between New York City and Columbus, Ohio.  

Following April’s record-breaking bolt event, another lightning megaflash ripped through the skies of Uruguay and northern Argentina during a thunderstorm on 18 June 2020. The flash lasted 17 seconds, breaking the record for the longest lasting lightning flash.  

Both events were considered cloud-to-cloud lightning flashes, lighting up the sky thousands of feet above the ground. Cloud-to-cloud lightning happens when a negatively charged cloud attracts a positively charged cloud. This type of lightning does not strike the ground, instead travelling from one cloud to another.  

Prior to the two new records, a megaflash over Brazil held the record for the longest flash by distance, spanning just over 709 kilometres (441 miles). Meanwhile, a megaflash lasting just under 17 seconds over neighbouring Argentina held the record for the longest duration. 

What is a megaflash? 

Megaflashes are a result of incredibly intense thunderstorms, called conductive thunderstorms. These types of thunderstorms are heat-based and are not associated with the weather fronts commonly occurring during the spring. When the conditions are just right, powerful lightning can strike in a flash—quite literally. 

“These are lightning flashes that travel for hundreds of miles and can last for many seconds, said Dr. Randall Cerveny, rapporteur of Weather and Climate Extremes for WMO. “They are luckily very rare, but they do occur.” 

Scientists are still researching what causes these monster storms. Dr. Cerveny says that the new records are not caused by climate change. Massive thunderstorms do not guarantee that megaflashes will occur, which is what makes these phenomena so rare. 

WMO Megaflashes

The new record strikes occurred in Mesoscale Convective System (MCS) thunderstorm hotspots. Although such storms can happen anywhere in the world, they are much more common over large landmasses close to the equator. These temperature dynamics allow remarkable atmospheric extremes to develop. Megaflashes tend to occur in lightning hotspots, such as the Great Plains in North America, and the La Plata basin in South America. 

“Right now, we think there are a couple of prime locations for these kinds of lightning events. We see them primarily in the midwestern and southern states, and down in South America in the Pampas region of Argentina.”  

However, Dr. Cerveny says as additional countries begin adopting weather satellite technology, scientists will have access to larger databases. This means there may soon be megaflash records forecasted in Eastern countries like China and India—areas that do not yet have long-term records established. 


How are megaflashes detected? 

Advances in space-based lightning mapping now allow researchers to measure the duration and distance of megaflashes. Scientists were previously limited to ground-based lightning mapping networks and other proven methods.  

“If you see a flash of lightning and start counting and you’re able to get to 5 before you hear thunder, it means the lightning flash was a mile away. If you get to 10, it means that the lightning flash was 2 miles away. Every five seconds equates to one mile.” 

While new technology may enable scientists to observe even greater weather extremes, the WMO Archive of Weather and Climate Extremes maintains a list of verified global records. 


“We’ve only found these lightning flashes in the last handful of years and we’re compiling records and still trying to figure out if we can have even bigger ones,” said Dr. Cerveny. “We have an instrument that is up on a satellite that can record lightning flashes, and that’s something that more than 10 years ago we didn’t have the capability of doing.”  

Other documented lightning-related records include:  

  • The highest concentration of lightning – Catatumbo, Venezuela receives almost 250 lightning flashes per square kilometre each year. 
  • The most strokes in a lightning flash – 26 pulses in a single flash, in a cloud-to-ground flash in New Mexico, 1962. 
  • The most common type of lightning – Intra-cloud lightning, often called sheet lightning, accounts for 90% of all lightning flashes. 
  • The most powerful lightning – Positive lightning strikes can strike at 300,000 amperes and a billion volts. 
  • The tallest lightning phenomenon – “Gigantic jets” occur as an upward projection above a thunderstorm associated with lightning and have reached 90 kilometres (56 miles) in height. 

Staying safe during a megaflash 

The new megaflash findings point out the danger of lightning. 

Lightning is one of the leading causes of weather-related fatalities, responsible for an average of 49 deaths each year, according to the National Weather Service.  

“Lightning can hit places very far away from where it starts. If you are in a place that has lightning going on, you should take immediate steps to save yourself. Get into a protective structure or a hard-top car with the windows rolled up. These are safe places because lightning doesn’t go through objects; it goes around objects.” 

The WMO hopes that these new records will persuade people to pay closer attention to lightning safety and take the appropriate precautions to stay safe. 

“People need to be aware of the dangers, particularly in places like Florida which is the lightning capital of the world.”