Even for Southerners used to spending a lot of time outside, this week’s brutal heat and humidity — which spread from Texas across the Gulf Coast States and north into Missouri, Tennessee and Arkansas on Wednesday — are a little much.
“It’s miserable,” said Kellie Tortorich, a teacher in Baton Rouge, La., who is out of school for the summer but is caring for two young children while pregnant with a third. “We prioritize being outside,” she said as her children, 4 and 6, emerged dripping wet from a splash park, “but it’s been hard at certain times of the day.”
An oppressive heat wave that baked Texas and Oklahoma last week, contributing to several deaths, has engulfed much of the southern and central United States, raising the heat index to dangerously high levels from Kansas City to the Florida Keys.
Temperatures will climb up to 20 degrees above normal for much of the region through at least the weekend, reaching the upper 90s or low 100s in many places, with the heat index — a measure of how heat and humidity make the air feel — soaring even higher.
“It’s not usually this hot in June,” Ms. Tortorich said.
Major cities where the heat index could reach between 110 to 120 degrees over the next few days include Dallas, San Antonio, New Orleans and Nashville, as well as Little Rock, Ark.; Jackson, Miss.; and Montgomery, Ala. “Many areas outside of Texas will experience their most significant heat of the season so far,” a forecast from the National Weather Service said.
Nighttime temperatures will offer little respite, staying unseasonably high even while the sun is down, and high humidity will continue to produce “potentially life-threatening” heat through the rest of the week, forecasters said. Health experts consider a heat index of over 103 degrees dangerous, with a higher risk of cramps, exhaustion and heat stroke, particularly after exercise or long stretches in the sun.
“It is essential to have ways to cool down and limit your heat exposure,” the Weather Service said on Twitter.
In Gulfport, Miss., the employees of Superior Detailing have to spend a lot of time outside, no matter the temperature. “We have to suck it up and go to work,” John LaCoste, who owns the car detailing business, said, “because we still have families to take care of and bills to pay.”
But his crews are slowing down and taking more breaks when needed, he said, adding that his customers don’t seem to mind. “Most people don’t want to get out in the heat and clean their cars themselves,” Mr. LaCoste said, “so they definitely get it.”
The heat will also rise in other parts of the country, including in Northern California — where cool weather and gloomy skies have reigned for several weeks. Sacramento and the San Joaquin Valley are under excessive heat warnings, the Weather Service said.
And though temperatures are not expected to be above average in the Southwest, dry conditions and low humidity, combined with gusty winds, will increase fire danger across much of Arizona, New Mexico and southwestern Texas.
The unusual early-summer temperatures across the South are the result of a stubborn “heat dome” of high pressure, akin to a lid on a pot that holds in steam, that has hovered over Texas and northern Mexico for more than a week. Forecasters have warned that the relentless heat could continue through the weekend across much of the South.
The heat will persist next week in some parts of the country, with parts of the Great Lakes, Midwest, Idaho and eastern Washington State expected to be up to 10 degrees above normal, said David Roth, a meteorologist with the Weather Prediction Center of the National Weather Service.
“This may be outside of what you would normally expect in summer,” Mr. Roth said. “Prepare for that.”
John Keefe contributed reporting.