Longest horizontal distance of a lightning bolt

What to remember

From Mississippi through Louisiana to Texas, a single lightning bolt spanned 829 km horizontally in 2020. It is the longest distance known for a lightning flash.

Such giant discharges have a name, megaflashes. They remain hard to observe and measure, and the technology for tracking them is advancing quickly, so records of extreme lightning are an emerging field, and scientists expect more length records in the future.

The same year produced another record: the longest-lasting bolt, more than 17 seconds, observed over Uruguay and northern Argentina. For energy, the strongest flashes are called superbolts, and their maximum energy is hard to pin down directly; satellites have recorded optical output of up to about 10 terawatts.