Texas is feeling an early heat wave. It’s a sign of a long, hot summer to come

By Andrew Freedman and Mary Gilbert, CNN

(CNN) — A dangerous round of early season extreme heat is on tap for parts of Texas this week in a prelude to what’s expected to be an abnormally hot summer across much of the United States.

Long-standing records could fall across central and southwest Texas, including in Austin and San Antonio, as temperatures reach highs that would be unusual for mid-summer, let alone early-to-mid May.

More than 6 million people in Texas are under heat advisories from the National Weather Service Tuesday and Wednesday, with one forecast office calling this early-season heat wave “potentially historic.”

• In Austin, Wednesday’s high of 107 degrees would make it the hottest day in May on record there. Tuesday’s high of 104 degrees would be the hottest temperature on record so early in the year, and the third-earliest date to hit triple-digits there.
• Temperatures in San Antonio could reach at least 103 degrees for three straight days starting Tuesday, a streak that has never been set there during May and is rare in any month.
• Del Rio’s high on Wednesday of 110 degrees would be the earliest it has hit 110 degrees and would tie for the 12th-hottest day on record. It would also be just 5 degrees shy of tying the city’s all-time record of 115 degrees.

Millions of people in central Texas, including the Austin metro area, will be in the National Weather Service’s “major” heat risk Wednesday. Such heat “affects anyone without effective cooling and/or adequate hydration,” the agency warns.

Parts of southern Texas, near the Mexico border, are forecast to be at risk of “extreme” heat—an unusually early appearance in the year for the highest risk level.

San Antonio and parts of the greater Houston area are at risk of “major” heat Thursday.

The heat is likely to pose a serious health threat simply because it’s the first heat wave of the season, and an early one, coming before people have become accustomed to high temperatures.

“The risk for heat related illness is higher than normal,” the Austin-San Antonio forecast office cautioned, particularly for vulnerable groups including the elderly and young children.

The unseasonably high temperatures could also stress Texas’ power grid with record or near-record demand. Texas, with its independent grid, is no stranger to extreme weather-related electricity problems, whether by heat waves or cold snaps. However, the state has added large amounts of solar power and battery storage since its winter power crisis in 2021.

Human-caused climate change is increasing the frequency and severity of extreme heat events in the US and around the globe.

And it’s supercharging Texas heat: Climate change has made San Antonio’s forecast high temperature on Wednesday about five times more likely than it would have been without fossil fuel pollution, according to the nonprofit research group Climate Central.

Before 2022, San Antonio had only seen two heat waves during which there were three straight days with highs of 105 degrees or hotter – this week could potentially bring the sixth such stretch in the last three years if temperatures climb just 1 to 2 degrees higher than currently forecast.

Heat is by far the deadliest form of severe weather in the US, killing on average twice as many people a year as tornadoes and hurricanes combined.

Early heat wave heralds another sizzling US summer

While summer heat elbows its way into spring, the actual summer months are shaping up to be warmer than normal for the entire US.

The latest forecast from the Climate Prediction Center paints a very toasty picture from June through August: Above average temperatures are likely over the Lower 48, Alaska and Hawaii this summer.

A sizzling summer is most likely in the West and parts of the South and Northeast — an outlook strikingly similar to last summer’s predictions. Last summer was the second-warmest on record for the West and the warmest on record for the Southwest. The Northeast had its fourth-warmest summer.

The summer outlook also includes a concerning precipitation trend for a large portion of the US that goes hand-in-hand with prolonged heat: Drier than normal conditions are expected for portions of the West, Midwest and much of the Plains.

Dryness and heat are cyclical. The hotter an area becomes, the more it dries out, which could be a recipe for new or worsening drought. A dry area will then get even hotter as most of the sun’s energy goes into heating the ground, with little energy lost to evaporation of wet soil.

It’s the opposite story for the East and Southeast, where wetter than normal conditions are likely — a projection that could be due in part to forecasts for an active hurricane season. Combine that with the anticipated heat, and it could be a humid summer for these areas.

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CNN Meteorologist Brandon Miller contributed to this report.