Twenty-three of the 25 fires so far this year were ignited by human activity. While this year’s heavy snowpack and cold spring pushed back the start to fire season in many parts of the state, climate change is generally causing an earlier snowmelt, said climatologist Rick Thoman.

On June 19, 2015, a slow-moving low-pressure system with spectacular thunderstorms that produced little rain began making its way through Alaska. By the time the storms finally petered out about a week later, 61,000 bolts of lightning had been unleashed on a boreal forest in the state. No one had ever seen anything quite like it, not even in 2004, when 8,500 lightning strikes were recorded in a single day.