Heat dome set to bring record temperatures across much of the contiguous United States
A large, persistent high-pressure system will drive temperatures 15-25 °F above normal for at least a week, prompting record heat and heightened wildfire risk.
A massive high-pressure ridge, often called a heat dome, is expected to settle over the Northern Plains this weekend and expand to cover as much as two-thirds of the contiguous United States for more than a week. The National Weather Service warns that temperatures could be 15 to 25 °F (8 to 14 °C) higher than average, with nighttime lows remaining unusually warm.
Meteorologists say the dome will trap hot air while blocking cooling winds and precipitation, creating conditions that could break or tie more than 90 local temperature records, many of them overnight highs. "Nights can be just as dangerous as days. If you don’t get heat relief at night, that’s going to spill out into your daytime experience and become extremely dangerous," said Bob Henson of Yale Climate Connections.
Forecasters anticipate triple-digit highs in Nevada, Utah, Colorado, Wyoming, Idaho, Montana, North Dakota and South Dakota, while the Southeast may see record nighttime warmth despite cooler daytime temperatures due to limited rain. Cities such as Fort Lauderdale, Miami, Tampa, Galveston and Charleston are projected to stay above 80 °F (27 °C) at night.
Experts note that the dome’s size, intensity and longevity are unusual, especially for its northern reach. Drought-stricken soils and low atmospheric moisture are expected to amplify the heat, creating a feedback loop that worsens drought and raises wildfire risk.
While a newly formed El Niño is not yet influencing the pattern, scientists attribute the heightened intensity and extent of the event to human-caused climate change. Daniel Swain of UC Agriculture and Natural Resources said heat waves are becoming more intense, longer-lasting and larger because of the long-term warming trend. Climate Central’s attribution analysis indicates that the heat experienced by 24 million people from Southern California to northern Minnesota is at least five times more likely because of greenhouse-gas-driven warming.