WMO Confirms Record-Breaking Megaflash Lightning Strike in USA
- Ritambhara K
- Aug 10
- 4 min read
WMO 2025 Calendar Competition - Photographer: Edward Mitchell
The World Meteorological Organization (WMO) has confirmed a new world record for the longest lightning flash—an astonishing 829 kilometers (515 miles)—recorded in a well-known storm hotspot in the United States.
This “megaflash” occurred in October 2017 during a massive thunderstorm complex, stretching from eastern Texas to near Kansas City. The distance is comparable to traveling from Paris to Venice in Europe, a journey that would take about eight to nine hours by car or at least 90 minutes by commercial plane.
WMO Secretary-General Celeste Saulo emphasized the dual nature of lightning as both awe-inspiring and dangerous: “Lightning is a source of wonder but also a major hazard that claims many lives around the world every year, making it a priority for the international Early Warnings for All initiative. These findings highlight significant safety concerns, as electrified clouds can generate flashes that travel vast distances, disrupt aviation, and ignite wildfires.”
The record was verified by WMO’s Committee on Weather and Climate Extremes, which uses the latest satellite technology to track global, hemispheric, and regional weather extremes. The measurement carries a margin of error of ±8 km (5 miles) and surpasses the previous record—768 ± 8 km (477.2 ± 5 miles)—set across the southern United States on April 29, 2020, by 61 kilometers.
This extraordinary event took place in the Great Plains of North America, a known hotspot for Mesoscale Convective System (MCS) thunderstorms, whose dynamics can produce such exceptional megaflashes. The full findings appear in the Bulletin of the American Meteorological Society.
Both the previous and current lightning flash records were measured using the same “maximum great circle distance” method to determine flash extent. The 2017 event stands out as one of the first storms in which NOAA’s newest Geostationary Operational Environmental Satellite (GOES-16) captured lightning “megaflashes”—extremely long-duration and long-distance lightning discharges.
Interestingly, this particular megaflash was not identified during the original 2017 storm analysis. It was discovered later during a re-examination of the thunderstorm data.
“This new record clearly demonstrates the incredible power of nature,” said Professor Randall Cerveny, WMO’s rapporteur of Weather and Climate Extremes. “Our assessment of environmental extremes, such as this lightning distance record, reflects the significant scientific progress made in observing, documenting, and evaluating such events. It’s likely that even greater extremes exist, and with continued high-quality lightning measurements, we’ll be able to detect them in the future.”
The WMO Archive of Weather and Climate Extremes keeps the official global, hemispheric, and regional records for a range of weather phenomena. Currently, it documents extremes for temperature, pressure, rainfall, hail, wind, and lightning, as well as records for two specific storm types—tornadoes and tropical cyclones.
The World Meteorological Organization (WMO) has previously documented several remarkable lightning extremes. These include the longest duration for a single lightning flash—17.102 ± 0.002 seconds—recorded during a thunderstorm over Uruguay and northern Argentina on 18 June 2020. Another record involves the deadliest direct strike, in which 21 people were killed by a single flash while sheltering in a hut in Zimbabwe in 1975. The deadliest indirect strike occurred in 1994 in Dronka, Egypt, when lightning hit a set of oil tanks, causing burning oil to flood the town and killing 469 people.
Lightning specialist and WMO committee member Walt Lyons explained that studying megaflashes is shedding light on mesoscale electrical charge variations within Mesoscale Convective System thunderstorms. He noted that these events also reveal the danger of the newly recognized “bolt from the gray”—similar to the “bolt from the blue” seen in isolated storms, but capable of traveling hundreds of kilometers from the main charge-generating region.
Lyons emphasized that the only truly safe places during a lightning event are substantial buildings equipped with wiring and plumbing, or fully enclosed metal-topped vehicles. Open structures, such as those at beaches or bus stops, as well as vehicles like dune buggies or motorcycles, do not offer adequate protection.
“If lightning is within 10 kilometers, as indicated by reliable lightning data, move immediately to a safe building or enclosed vehicle,” he advised. “These extreme cases show that lightning can strike from long distances within seconds, but they are always part of larger thunderstorms—so situational awareness is key.”
Space-based technology
Previous assessments that established records for lightning flash duration and extent relied on data from ground-based Lightning Mapping Array (LMA) networks. However, many lightning scientists recognized that LMAs have inherent observational limits, restricting the scale of lightning events they can detect. Capturing megaflashes that exceed these limits would require lightning mapping technologies capable of monitoring much larger areas.
Recent advancements in space-based lightning mapping have overcome these challenges, enabling continuous measurements of flash extent and duration over vast geographic regions. Key among these instruments are the Geostationary Lightning Mappers (GLMs) aboard the R-series Geostationary Operational Environmental Satellites—GOES-16, GOES-17, GOES-18, and GOES-19—which recorded the new lightning distance record. Similar capabilities are now available from Europe’s Meteosat Third Generation (MTG) Lightning Imager and China’s FY-4 Lightning Mapping Imager.
“The extremes of lightning are challenging to study because they push the limits of what we can realistically observe,” said Michael J. Peterson, lead author and evaluation committee member from the Severe Storms Research Center at the Georgia Institute of Technology, USA. “Adding continuous measurements from geostationary orbit has been a major breakthrough. Today, most of the world’s megaflash hotspots are within the observation range of geostationary satellites, and improved data processing allows us to accurately capture flashes across the vast volume of available observations.”
Peterson added, “As the global data record grows, we’ll be able to detect even the rarest extreme lightning events and better understand their broad impacts on society.”
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