Most often lightning happens in a fraction of a second. If you blink or am facing the wrong direction, you’ll miss it.
But in the early morning of June 18, 2020, five years ago today, one lightning flash detected by satellite lasted a whopping 17. 1 seconds as it snaked across the sky from the Argentina-Uruguay border to just south of La Plata, Argentina.
A panel of lightning scientists together with the World Meteorological Organization later found this was the longest-lasting lightning flash on record anywhere in the world. It was about 320 miles from the point where the flash started to its endpoint, as you can see in the map below at left.
According to a 2022 study on the event, these so-called “megaflashes” aren’t generated by single thunderstorms, but rather in a smaller sample of large thunderstorm clusters known as mesoscale convective systems.
Earlier in 2020, another megaflash near the Gulf Coast was found to be the world’s record longest, extending 477 miles from coastal Texas to southern Louisiana.
June 2020 Uruguay record time megaflash
Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.