A powerful and unusually persistent heat dome is forecast to drive dangerous temperatures across much of the United States from this weekend, with forecasters warning that millions of people could face prolonged, life-threatening heat. Meteorologists say the sprawling high-pressure system will push temperatures 15 to 25 degrees Fahrenheit above seasonal averages, affecting as much as two-thirds of the continental US and potentially lasting for more than a week. Records set to tumble The heat dome is expected to establish itself over the Northern Plains before expanding across much of the country, trapping hot air and preventing cooler weather systems from moving in. Triple-digit temperatures are forecast in parts of Nevada, Utah and Montana, with more than 90 local temperature records expected to be equalled or broken by Wednesday. As the system shifts eastward, forecasters warn the extreme heat could eventually stretch from coast to coast. Night-time heat raises alarm Meteorologists say one of the greatest dangers will come after sunset, as unusually warm overnight temperatures prevent the human body from recovering from intense daytime heat. The Southeast could experience exceptionally high overnight temperatures, with added humidity making conditions even more oppressive. Experts warn that sustained heat exposure significantly increases the risk of heat exhaustion, heatstroke and other serious health emergencies. Health risks intensify Forecaster Bob Henson warned that extreme heat should be treated with the same seriousness as tornadoes or hurricanes because of its ability to cause widespread illness and fatalities. Emergency officials are expected to monitor vulnerable groups closely, including older people, young children and those with underlying health conditions, as the prolonged heatwave develops. Climate change fuels extremes Climate scientists say human-driven climate change is increasing both the frequency and intensity of extreme heat events. Rising global temperatures caused by greenhouse gas emissions have made prolonged heatwaves significantly more likely and more severe. Researchers estimate that an event of this scale is at least five times more likely because of climate change, reinforcing concerns that prolonged periods of dangerous heat are becoming an increasingly common feature of summer across large parts of the United States. Huge 'heat dome' set to bring record temperatures to US
