Study: Climate Change Extends Wildfire Nighttime Hours

A new study reveals that climate change is eroding the traditional nighttime lulls in wildfire activity across North America, extending the hours when conditions favor burning and complicating efforts to contain blazes.

Researchers from Canadian institutions, including the University of Alberta and Natural Resources Canada, analyzed hourly satellite data from nearly 9,000 wildfires between 2017 and 2023. They developed a machine-learning model to estimate fire-conducive conditions back to 1975, finding that such hours have increased by 36 percent continent-wide over the past five decades. In some northern regions, like parts of Alberta and the Northwest Territories, days with potential for round-the-clock burning have surged by 232 percent, while days exceeding 12 fire-friendly hours rose by 80 percent.

The shift stems from warmer temperatures, reduced nighttime humidity and stronger winds, which dry out vegetation and prevent fires from subsiding after sunset. "Fires normally slow down during the night, or they just stop," said Xianli Wang, a coauthor and fire scientist with the Canadian Forest Service. "But under extreme fire hazard conditions, fire actually burns through the...