Despite widespread drought in the West, wildfires have burned less than half the 10-year average area so far this summer.
U.S. Forest Service Chief Tom Tidwell said Wednesday that largely has been a matter of luck, with the hot, windy weather known as "red flag" days not lining up with the lighting strikes that start fires, particularly in California.
But he says that is changing. Eighteen large fires are burning in the Northwest with intensities not normally seen until August.
Firefighters on Wednesday were chasing 25 new fires ignited by thunderstorms moving across Northern California, Oregon and Washington.
Meanwhile, the Union of Concerned Scientists released a report warning climate change is contributing to bigger and longer fire seasons, and new homes in forests are driving up firefighting costs.