A scorching early-summer warmth wave that has baked much of Texas and Oklahoma for the previous week was spreading across the Gulf Coast on Tuesday, with harmful warmth forecasts reaching all the best way to the Florida Keys.

In Austin, Texas, the place the warmth index climbed to 118 levels Fahrenheit final week — the very best on report within the metropolis — officers have been getting ready for every day excessive temperatures to stay above 100 “for the foreseeable future,” mentioned Kevin Snipes, town’s emergency administration director.

Ambulance calls and emergency-room visits for warmth exhaustion have risen in Austin and different cities, together with Tulsa, Okla., the place electrical energy was out for tens of hundreds of individuals for a number of days final week after heavy storms that were followed by triple-digit heat.

The excessive temperatures have already confirmed deadly for some. A teenage boy from Florida and his stepfather, who have been climbing in Big Bend National Park in southern Texas on Friday, died as temperatures there rose to 119 levels Fahrenheit — the second-highest mark ever recorded within the state.

“We are in extreme heat right now,” mentioned Thomas VandenBerg, a park ranger at Big Bend. The rising demand for electrical energy to chill properties and companies has additionally put a pressure on Texas’ independent power grid, although it seems to have held to date.

The uncommon early-summer temperatures — every day highs within the low 90s are extra typical for a lot of the area in late June — are the results of a cussed “heat dome” of high pressure that has lingered over a lot of Oklahoma, Texas and northern Mexico for days.

Determining whether or not a selected warmth wave is tied to local weather change requires evaluation. But even so, scientists have little question that warmth waves all over the world have gotten hotter, extra frequent and longer lasting. The 2018 National Climate Assessment, a major scientific report by 13 federal companies, famous that the frequency of warmth waves within the United States jumped to six a year by the 2010s, from a mean of two a yr within the Nineteen Sixties.

Forecasters count on the present warmth dome to shift slowly to the north and east during the week, extending the brutally sizzling climate to components of Louisiana, Arkansas, Mississippi, Alabama, Missouri, Tennessee, Georgia and Florida. The warmth index — a measure of how the air feels that takes into consideration each temperature and humidity — will push nicely into the triple digits in the course of the day in a few of these areas, and temperatures gained’t cool a lot in the course of the night.

The sample may proceed throughout a lot of the South by the Fourth of July vacation, with maybe the most important variety of individuals affected on Wednesday and Thursday.

John Keefe and Jacey Fortin contributed.