Hotter nights threaten health, complicate wildfire fight
Most of the continental United States is about to experience an unusually large, strong and long-lasting heat dome that will push temperatures 15 to 25 degrees Fahrenheit (8 to 14 degrees Celsius) above normal, according to meteorologists.
The National Weather Service described the incoming heat wave as “significant and dangerous.” The system, a dome of high pressure that traps heat and humidity, began this weekend and is expected to last at least a week, with some areas feeling its effects until the end of the month, forecasters said.
Its immense size means it will cover as much as two-thirds of the continental United States, trapping high temperatures across a vast area that extends well beyond the Northern Plains where the high-pressure system is centered.
Hotter nighttime temperatures are especially bad for human health, meteorologists said. The sustained warmth at night also complicates efforts to contain an already active wildfire season, according to forecasters.
Daniel Swain, a climate scientist with the University of California Agriculture and Natural Resources, said the event stands out for its combination of scale, duration and intensity. “This is going to be a long duration, widespread and high-intensity heat event that’s going to affect millions of people for over a week,” Swain said.
The heat wave follows a summer of repeated extreme heat events across the United States, including a late-June heat wave that placed approximately 120 million people under extreme heat warnings during the July 4 holiday period.