A dangerous heat wave is taking shape across the United States, threatening to bring extreme temperatures to a vast portion of the country. Triple-digit highs are expected in the Southwest and Great Plains this weekend, with the heat then pushing eastward beneath a high-pressure dome that weather experts say could lock in oppressive conditions for a week or longer.
Weather forecasters are urging people to drink plenty of water and seek out air-conditioned spaces. Temperatures in many areas are expected to run 15 to 25 degrees Fahrenheit — or 8 to 14 degrees Celsius — above seasonal norms. What makes this event especially dangerous is that the heat won’t let up after sunset, leaving the human body no time to recover overnight.
“The heat doesn’t necessarily stop when it’s dark out,” said Josh Adam, a meteorologist with the National Weather Service in Bismarck, North Dakota. Temperatures there are forecast to exceed 100 F (37 C) through Tuesday — a dramatic departure for a state where summer highs typically hover in the 80s, Adam noted.
The National Weather Service projects that more than 90 local temperature records across the country will be tied or broken by Wednesday. Roughly two-thirds of those records are expected to be overnight heat records. Cities including Fort Lauderdale, Florida; Miami; Tampa, Florida; Galveston, Texas; and Charleston, South Carolina are forecast to see nighttime lows stay above 80 F (27 C).
Chad Merrill, a senior meteorologist with AccuWeather, described the current heat dome as one of the strongest to hit the Dakotas in 25 years. A heat dome forms when high pressure traps hot air in place while blocking the cooling effects of wind and rain.
Record-breaking triple-digit temperatures this weekend are expected across Nevada, Utah, Colorado, Wyoming, Idaho, Montana, North Dakota, and South Dakota.
Andrew Gorelow, a meteorologist with the National Weather Service in Las Vegas, said Nevada — a state no stranger to intense heat — is running even hotter than usual. Las Vegas is forecast to reach 111 F (48 C) on Saturday, Gorelow said.
Experts are stressing that staying hydrated and finding cool environments is essential during this event. They are also cautioning that the extreme heat could elevate wildfire danger in already-dry regions, particularly in the Rockies, where Merrill said dry thunderstorms may develop.
Scientists note that climate change, driven by the burning of coal, oil, and natural gas, is making heat waves more intense, longer-lasting, and more geographically widespread.
This year’s temperatures are also expected to be influenced by El Nino — a natural warming of the equatorial Pacific Ocean that disrupts weather patterns and pushes temperatures higher around the world. The current El Nino formed last month and is considered too new to have significantly contributed to this particular heat wave. However, experts say it has an 81% chance of reaching “very strong” status — the highest category — by fall, according to the U.S. National Oceanic and Atmospheric Administration, which made that announcement Thursday.
