"Climate change, including increased heat, extended drought, and a thirsty atmosphere, has been a key driver in increasing the risk and extent of wildfires in the western United States," the National Oceanic and Atmospheric Administration says.

Economic losses and damage are an estimated $135 billion and $150 billion, the costliest fire event in US history. Hurricane Helene in six states last fall caused up to $250 billion in damage.

Fierce wildfires are raging in the Los Angeles area, with fast-moving flames burning through homes and businesses. Residents are fleeing smoke-filled canyons.