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A World Meteorological Organization weather and climate extremes committee has judged that the world’s longest reported distance for a single lightning flash occurred with a horizontal distance of 321 km (199.5 mi) over Oklahoma in 2007, while the world’s longest reported duration for a single lightning flash is an event that lasted continuously for 7.74 s over southern France in 2012. In addition, the committee has unanimously recommended amendment of the AMS Glossary of Meteorology definition of lightning discharge as a “series of electrical processes taking place within 1 s” by removing the phrase “within 1 s” and replacing it with “continuously.” Validation of these new world extremes 1) demonstrates the recent and ongoing dramatic augmentations and improvements to regional lightning detection and measurement networks, 2) provides reinforcement regarding the dangers of lightning, and 3) provides new information for lightning engineering concerns.

A reduction by a factor of 10 in the population-weighted rate of lightning-caused deaths over the last century has been determined in several previous studies. The reasons have been attributed to a number of factors, but none have been quantified in detail with a large dataset. Several thousand lightning-caused deaths, injuries, and reports of property damage in the United States from 1891 to 1894 were analyzed manually from descriptions provided by an 1895 data source. A similar manual analysis was made of information in the NOAA publication Storm Data 100 yr later, from 1991 to 1994. Comparisons show that the decrease in lightning risk to people coincides with a shift in population from rural to urban regions. Major changes in the types of property damaged by lightning between the two periods 100 yr apart are also shown. In addition, the results identify significant shifts in the kinds of incidents in which people and objects are impacted by lightning. This information can help in the development of better guidelines for lightning safety and education.