Texas Heat Wave Shows No Signs of Letting Up

A weather pattern that has brought unrelenting heat to Texas for more than a week is unlikely to end until at least early July, according to forecast models, with record-breaking heat expected to expand into nearby states this weekend.

“It feels like you stuck your head in an oven,” said Tom Decker, a forecaster with the National Weather Service in San Angelo, Texas, describing what it has been like when he stepped outside this week. The temperature recorded at his forecast office tied its record of 111 degrees on Monday and shattered it again on Tuesday and Wednesday with readings of 114 each day.

When it is this bad, Mr. Decker said, he spends most of his time in an air-conditioned office or home. But he is concerned for people who don’t have that luxury, such as the crews drilling for oil, and the ranchers and the farmers in his forecast region.

The heat will become more dangerous and potentially deadlier as it persists in the coming days, especially for people exposed to it repeatedly and for long durations, forecasters with the Weather Prediction Center warned.

“Not only are the daytime temperatures and dew points abnormally high, producing some record heat index readings, but the overnight lows are also close to or at record levels,” said Alex Lamers, a forecaster with the Weather Prediction Center.

Officials in Texas asked residents to conserve electricity amid concerns that several days of triple-digit temperatures could strain the power grid. Early Friday, more than 100,000 homes and businesses were without power across Texas, Louisiana and Oklahoma, according to poweroutage.us, a website that tracks utilities.

According to New York Times estimates, on Friday more than 33 million people in the United States were expected to experience dangerous heat indexes — a measure of what the air feels like when considering both the air temperature and the humidity. The population affected is expected to grow this weekend as the dome of high-pressure shifts to include places like New Orleans, which is often humid in the summer.

Extended periods of high daytime temperatures with little relief at night, such as those accompanying this heat wave, create cumulative physiological stress on the human body, according to the World Health Organization, exacerbating the top causes of death globally.

San Antonio may have seen some of the worst conditions. Through Wednesday, the city had 21 hours with a heat index above 110 degrees over the course of the previous week. Since 1946, the city had previously only recorded 18 such hours over the same time period, Mr. Lamers said.

As the heat continues through the weekend, it will spread into Oklahoma, Kansas and Arkansas, where temperatures are likely also to exceed 100 degrees by the middle of next week.

Mr. Lamers and other forecasters said they were confident this weather pattern would persist through the Fourth of July.