On Sunday, August 27, I went mountain climbing in Olympic National Park, near my home. I noted how warm the day was — far warmer, even in early morning, than the norm for this time of year. I would learn that evening that across Puget Sound in Seattle, the city had seen temperatures an average of nearly 10 degrees above normal that day.

When I reached the top of the peak and looked to the northeast, a massive smoke plume from wildfires to the south clouded the horizon nearly all the way to the Canadian border. The Pacific Northwest has spent much of the summer covered in…