Another round of powerful storms brought rain, high winds and large hail to Texas on Tuesday, causing widespread damage, knocking out power to more than a million utility customers and halting flights for several hours at Dallas Fort Worth International Airport.
The storms left widespread damage across the Dallas area, including felled power lines, uprooted trees, and tractor-trailers that were overturned, according to the National Weather Service.
By Tuesday evening, over 800,00 customers were still without power, most of them concentrated in North Texas and the eastern part of the state, according to PowerOutage.us, which aggregates data from utility companies across the country. Judge Clay Lewis Jenkins, the top executive in Dallas County, said on Tuesday that power could be out for days, and that the authorities were prioritizing restoring service at hospitals and law enforcement buildings. Hospitals were operating on generator power, he added.
Central Texas faced the greatest risk of severe weather on Tuesday afternoon, with forecasts showing a moderate risk over a melon-shaped area that included Abilene, Waco, Austin and Midland. Amarillo, Dallas and San Antonio were also at risk.
The severe weather threat comes as more than 2.6 million people were under a heat advisory across South Texas, which has been gripped by oppressively hot weather for days.
A line of thunderstorms with wind gusts of up to 86 miles per hour was recorded in the Denton area, northwest of Dallas, and a second round brought winds of about 60 m.p.h., said Tom Bradshaw, a meteorologist at the Weather Service office in Fort Worth.
The storms included damaging winds, with gusts as high as 70 m.p.h. and hail the size of golf balls, the Weather Service said on social media.
Matt Stalley, a meteorologist at the Weather Service office in Fort Worth, said the agency had no plans to assess whether any tornadoes had touched down, adding that much of the damage across the area was likely caused by powerful straight-line winds.
By noon, the storm activity had moved beyond the eastern fringes of the Dallas-Fort Worth area, but there was a “decent chance we will have another round” on Tuesday night, Mr. Bradshaw said.
Parts of Texas were also facing extreme heat on Tuesday. The heat index in Laredo was expected to reach 115 degrees, while the heat index in Brownsville and Corpus Christi was also expected to reach the triple digits.
“We’re rivaling what is typically more like the summertime,” Tim Humphrey, a meteorologist with the Weather Service in Corpus Christi, said.
By Tuesday, the Corpus Christi area had recorded eight consecutive days in which the temperature has not dropped below 80 degrees, even at night, Mr. Humphrey said.
“When it’s very warm during the overnight hours, your body just doesn’t have that time to recover,” he said.
Much of Mexico has been gripped for several days by a heat wave that has killed dozens of howler monkeys and prompted rolling blackouts. The brutal heat across South Texas has been the result of hot temperatures shifting northward from Mexico as warm waters in the Gulf of Mexico have brought humid conditions to the state, Mr. Humphrey said. The humidity and high temperatures have combined to create dangerous heat index values across much of South Texas, he said.
The storms in Texas come on the heels of severe weather that stretched across much of the country over the holiday weekend. Storms and tornadoes killed at least 23 people from Texas to Virginia and left hundreds of thousands of customers without power. Heavy rain and damaging winds snarled holiday travel plans from the Midwest to the East Coast.
Texas has had a particularly bad spate of weather this spring, with heavy rain inundating parts of the state just weeks ago.
Elections officials in Dallas County said that the severe weather delayed the start of a runoff election. Mr. Jenkins said 103 election locations were without power, but another 180 places were open.
Grant Cruise, a spokesman for Oncor, a Texas electricity provider, said at a news conference that crews were assessing the damage on Tuesday. He said the response was more a matter of “complete reconstruction” rather than the simple repair of downed power lines.
“We are asking for your patience,” he said.
Heath Montgomery, a spokesman for Dallas Fort Worth International Airport, said that the Federal Aviation Administration grounded flights there from 5:30 a.m. to 8 a.m. About 90 flights were canceled for the day, and a number of flights were diverted to other airports, he said.
Beyond Texas, Kentucky is expecting a reprieve in the coming days, as the National Guard and forestry workers continue to clear downed trees and dangerous debris from powerful storms that killed four people over the weekend. The Weather Service in Louisville said that mostly dry weather was expected in the coming days, with no rain in the forecast until the weekend.
Severe storms were possible across Central Oklahoma on Tuesday, beginning early in the morning and shifting south through the afternoon, according to the Weather Service office in Norman, Okla. In Southern Oklahoma, raging storms with large hail had become less intense by early Tuesday morning, the Weather Service said. Still, hail the size of golf balls and damaging winds of up to 60 m.p.h. were possible later in the day. Two people were killed north of Tulsa over the weekend as severe storms swept in.
After a wet, windy and disruptive Memorial Day in the Mid-Atlantic and Northeast, sunny, summerlike conditions returned on Tuesday morning with highs in the low-to-mid 80s.
There were 2,000 delays and 300 cancellations of flights into, within or out of the United States on Tuesday, according to FlightAware, a flight tracking website. On Friday, more than 2.9 million people were screened at U.S. airports, the Transportation Security Administration said, a single-day record.
Christine Hauser, Jesus Jiménez and Ernesto Londoño contributed reporting.