A lightning bolt that stretched 829 kilometers (515 miles) across the southern U.S. has set a new world record for the longest single lightning flash, according to the World Meteorological Organization (WMO). The bolt occurred during a massive thunderstorm over Texas in October 2017 and reached near Kansas City, Missouri.
The event was detected using next-generation satellite technology, which helped scientists identify this rare “megaflash” — a type of lightning that travels horizontally through sprawling cloud systems rather than striking straight down.
A massive lightening bolt that stuck across the skies of USA has officially set a new world record. Known as a Megaflash this single lightning event stretched an astonishing 829 km from Eastern Texas to near Kanas City, Missouri.#TemptationIsland2025 pic.twitter.com/tNzXEFrnWa
— Bil@l Ahm@d Kh@n (@bili_butcher) August 1, 2025
Megaflashes form in “mesoscale convective systems,” vast networks of thunderstorms that create ideal conditions for long-distance electrical discharges. Though they look like ordinary lightning to the naked eye, only satellite imagery reveals their true scale. A single megaflash can release multiple cloud-to-ground strikes across hundreds of kilometers in a matter of seconds.
Researchers say megaflashes typically form in the weaker, outer parts of storm systems, not the intense core. The record-setting flash followed this pattern, threading through wide, flat cloud layers behind a cold front. These conditions allowed the electric charge to travel over immense distances without interruption.
While megaflashes are most common in the U.S., experts say parts of northern and northwestern Australia — such as the Top End and Kimberley — also see storm systems capable of producing them. However, limited satellite coverage means many may go undetected.
As storm-monitoring tools improve, researchers expect to find even longer flashes. With climate change intensifying storms globally, lightning frequency — and the occurrence of megaflashes — may also increase.
