Scientists have now observed the largest megaflash lightning strike ever documented, stretching from Texas to Kansas City across 515 miles of the Great Plains, as revealed in a recent study.
“We call it megaflash lightning and we’re just now figuring out the mechanics of how and why it occurs,” said co-author Randy Cerveny, an Arizona State University President’s Professor in the School of Geographical Sciences and Urban Planning.
“It is likely that even greater extremes still exist,” he adds, “and that we will be able to observe them as additional high-quality lightning measurements accumulate over time.”
Megaflash Lightning
On October 22, 2017, a massive thunderstorm erupted with a lightning strike, and it turned out to have outdone the previous record by 38 miles, which had not yet even been established. The team responsible for the discovery reanalyzed old storm data collected by space-based instrumentation for their measurements of these record-breaking megaflashes.
Only a slim figure of less than one percent of thunderstorms produce mega flashes. The vast majority of strikes travel under 10 miles, well below the 60-mile threshold required to be considered a megaflash. To generate these extreme events, storms require long-term activity, usually lasting at least 14 hours, and must be enormous, roughly equivalent to that of New Jersey, producing five to seven electrical branches in a single strike.
NEXRAD radar reflectivity imagery. Credit: World Meteorological Organization, American Meteorological Society
New Tools for Weather Monitoring
The smaller, localized scale of the lightning detection apparatus left megaflashes poorly observed until recent years. Traditionally, ground-based antenna networks detected radio signals coming from lightning strikes, triangulating the speed and location of the strikes based on the points in time at which different network nodes made their detection.
A major innovation, vastly expanding the scope of lightning detection efforts, emerged with the introduction of satellite-based lightning detection instruments in 2017. With their view from space, these new observation technologies can accurately measure megaflashes on a continental scale.
“Our weather satellites carry very exacting lightning detection equipment that we can use to document to the millisecond when a lightning flash starts and how far it travels,” Cerveny said.
The National Oceanic and Atmospheric Administration (NOAA) operates the GOES-16 satellite, which, during its orbits around the planet, detects millions of lightning strikes daily, along with three other NOAA satellites. Since GOES-16’s launch in late 2016, Europe and China have launched similar weather monitoring satellites.
“Adding continuous measurements from geostationary orbit was a major advance,” said lead author Michael Peterson of the Georgia Tech Research Institute. “We are now at a point where most of the global megaflash hotspots are covered by a geostationary satellite, and data processing techniques have improved to properly represent flashes in the vast quantity of observational data at all scales.”
Lightning Safety
Given the tremendous distances lightning can travel, the researchers urge the public to exercise greater caution when it comes to lightning safety. The types of record-breaking megaflashes discovered in the new work are exceedingly uncommon, but even relatively routine storms can generate ten-mile or greater strikes.
Cerveny notes that in light of 20 to 30 lightning deaths and hundreds of injuries in the US annually, the public needs to be more aware of the distance lightning can travel and that most strikes occur before or after the storm peak, not during it.
“That’s why you should wait at least a half an hour after a thunderstorm passes before you go out and resume normal activities,” Cerveny said. “The storm that produces a lightning strike doesn’t have to be over the top of you.”
The paper “A New WMO-Certified Single Megaflash Lightning Record Distance: 829 km (515 mi) Occurring on 22 October 2017” appeared on July 2, 2025, in the Bulletin of the American Meteorological Society.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.