Lightning

Dry lightning (without the dampening effect of precipitation), can ignite fires anywhere, but in remote regions where fire-suppression activity is limited or nonexistent, they can spread, sometimes into urban areas or the wildland-urban interface, damaging property and impacting health. Although approximately thirty percent of wildfires in the Western U.S. are caused by lightning, such fires account for more than half of the total area burned on an annual basis and the ones that do occur can be devastating.¹ In 2020 alone, a series of 650 wildfires were ignited in California by dry lightning from thunderstorms spawned in part from Tropical Storm Fausto.² The fires collectively burned between 1.5-2.1 million acres. Although northern Canada and Alaska are not in the domain of the Verisk model, it is relevant to note that a study by Veraverbeke et al. (2017) found historical trends in lightning-initiated fires and that future increases in Canada would likely be significant because very large fires can grow in very remote locations.³ Studies of trends or future impacts of lightning changes on wildfire activity have not been conducted for Western U.S. although a study conducted by Romps et al. (2014) did conclude that climate change would bring an increase in lightning activity in the lower 48 states.