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By Amanda Castro
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A new heat dome has tightened over the south‑central United States, sending temperatures back toward triple‑digit territory even as the region approaches the autumn equinox.
The surge extends one of the most extreme warm spells on record for Texas, Oklahoma, Arkansas and neighboring states. Millions now face another week of dangerous heat, worsening air quality and the potential for storms forming along the dome’s edges as the pattern expands eastward.
The ridge arrives after a summer that broke temperature records across the Lower 48 and coincides with global heat milestones, making August 2026 one of the hottest months ever measured on Earth.
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Heat Dome Rebuilds Over Texas and Oklahoma
The latest dome formed over familiar ground—Texas, Oklahoma, Arkansas, Louisiana and parts of the Southeast—where high pressure has repeatedly parked since spring.
Even with the sun weakening as the equinox nears, temperatures are running 5 to 10 degrees above historical averages.
Highs in the upper 80s and 90s are widespread, but the core of the dome is pushing Dallas, Austin and Oklahoma City back toward 100 degrees through Saturday.
“There are multiple reasons for this heat dome to be so persistent across the southern US, and it has to do with other teleconnections in the Pacific that are not related to El Niño,” Senior Meteorologist at AccuWeather Alan Reppert told Newsweek. “While El Niño is playing a role, there are other sea surface temperature teleconnections that have been in favorable phases to keep the heat dome centered over the southern US.”
Reppert added that El Niño’s influence typically strengthens in winter and takes time to shape weather patterns. That lag has allowed other ocean‑driven signals to dominate the late‑summer setup.
Record‑Breaking 100‑Degree Streaks Across the Region
The dome is landing on top of an already punishing season. Dallas has recorded 49 days at or above 100 degrees—nearly double its 20‑year average—while Oklahoma City has more than tripled its typical count.
September alone has delivered 10 triple‑digit days in Oklahoma City and 12 in Dallas, an uncommon but not unprecedented stretch.
“Dallas and Oklahoma City have had a lot of 100-degree days, with Oklahoma City having 10 100-degree days alone in September,” Reppert said. “While this is an impressive stretch of days, this has happened before, but it is uncommon to occur.”
Other cities are also nearing historic benchmarks. Austin has reached 43 days above 100 degrees, compared with a 20‑year average of 29.
El Paso has hit 52 such days, far above its typical 34. Little Rock, Tulsa and Wichita have all doubled or tripled their long‑term norms.
Ocean Temperatures and El Niño Help Fuel the Ridge
Warm oceans are reinforcing the dome’s strength.
“El Niño and the ocean temperatures are playing some part in this heat dome,” Reppert said. “Warmer sea surface temperatures tend to help aid in the strengthening of areas of high pressure.”
He noted that waters off the West Coast have been warm enough to help sustain the ridge, while the Gulf of Mexico has also run above historical averages.
Those conditions have repeatedly recharged the dome as it rebuilds across the southern U.S.
August 2026 tied July 2023 as the hottest month ever recorded, with global average surface temperatures reaching 16.96°C (62.5°F).
Sea‑surface temperatures outside the polar regions hit their highest August values on record, averaging 21.07°C, and daily readings peaked at 21.11°C on August 24 and 25.
Who Is Most Vulnerable Under the Dome
The dome’s footprint covers some of the country's most heat‑prone terrain.
“Most of Oklahoma, Texas, and Arkansas are susceptible to this heat as most of these three states have been hot,” Reppert said. “Parts of western Texas and western Oklahoma can be cooler as those areas are higher than eastern parts of each of those states, helping to shave a few degrees at least off the temperatures.”
Combined with humidity and stagnant air, the dome is producing poor air quality across multiple states. Vulnerable residents—including older adults, outdoor workers and those without reliable cooling—face heightened risks as the pattern persists.
Meanwhile, parts of the Northeast are bracing for their first frost of the season, highlighting the stark regional contrast.
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Storms Forming Along the Dome’s Edges
As has been the case all summer, the dome’s boundaries are fueling rounds of downpours and severe thunderstorms. This week, storms are expected from the Dakotas and eastern Montana through western Minnesota, the Midwest and into the Northeast.
A storm could also form off the Atlantic coast and drift southwestward across Florida into the Gulf of America. Lower pressure from that system could initiate a tropical or subtropical depression. Another area southeast of Bermuda has a medium chance of developing.
These edge‑driven storms have been a defining feature of the season, repeatedly forming where hot, stagnant air meets cooler surrounding zones.
Global Heat Context and What Comes Next
Reppert said the southern U.S. heat dome contributed “a little bit” to August’s global record but emphasized that Europe saw even greater departures from historical averages.
“The southern US was only a small piece to a much larger puzzle for beating the record for August,” he said.
Relief may finally be approaching. “The heat is expected to start to lose intensity late this week and into the weekend as a more active northern Pacific jet stream will help to dislodge the heat dome and bring relief to the southern US,” Reppert said.
Even so, the summer’s legacy is already cemented. The Lower 48 averaged 76.9 degrees in July—breaking records dating back to 1895 and surpassing the extreme heat of July 1936 during the Dust Bowl.
With heat domes repeatedly rebuilding since spring, the south‑central U.S. has endured one of its hottest warm seasons on record.
Contact Newsweek editors on this story: Samantha Beech and Gray R. Thomas
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