The temperature gauge in a car shows 101 degrees Fahrenheit (38.3 degrees Celsius) in downtown Houston, Texas, United States, on June 15, 2023. From US south central state of Texas to southeastern Florida, about 35 million people are bracing for a widespread heat wave which is expected to last for days, the US National Weather Service (NWS) forecast on Thursday. Photo:Xinhua

From US south central state of Texas to southeastern Florida, about 35 million people are bracing for a widespread heat wave which is expected to last for days, the US National Weather Service (NWS) forecast on Thursday.

The heat wave in parts of Texas, Louisiana and Florida is likely to break records and raise the risk of wildfires and heat-related illnesses, the weather service warned.

"It wouldn't be an active summer weather pattern without oppressive heat and much of Texas and the Deep South will have plenty heading into the beginning of the holiday weekend," the NWS said in its forecast.

Record-setting June heat wave is building up in many parts of Texas. The Dallas-Fort Worth area in northern Texas is forecast to see heat index readings of 105 to 112 degrees Fahrenheit on Thursday or Friday, the weather service said, adding that high temperatures in the area could hit triple digits by early next week, earlier than average to the region.

In Austin, the capital city of Texas, the hottest June 14-20 period is on record with an average high temperature of 104 degrees Fahrenheit over the next week, the First Warning Weather team predicted.

A new tool developed by the Climate Central, known as the Climate Shift Index, attributes the heat wave to manmade climate change by showing fingerprints of climate change on day-to-day weather at a particular location.

According to Climate Central's analysis, Austin's high temperatures by Thursday afternoon exceeding 100 degrees Fahrenheit are at least five times more likely because of climate change.

"The types of temperatures that we're seeing this week are extremely unlikely to happen in a world without climate change," Massachusetts Institute of Technology climate scientist Dr. Daniel Gilford, who works with Climate Central, told local media outlet KHAN earlier this week.

Later this week or early next week, the heat index in southern and western Texas could climb up as high as 120 degrees, according to the NWS, warning health risks for people working outdoors or living indoors without air conditioning.

Amid the heat wave, electricity demand is expected to rise in Texas, the second most populous state in the United States, later this week, the Electric Reliability Council of Texas which manages about 90 percent of the state's electricity load, said in a statement on Wednesday night.

However, power supply will be enough to meet the demand and an "energy emergency" is not expected, said the council.

A heat advisory was also put in effect from 11:00 a.m. through 7:00 p.m. Thursday local time in the coastal state of Louisiana. Though high temperatures were forecast to stay in the mid and upper 90s, the high humidity will make it feel like 105 to 110 degrees and it will feel even hotter in the direct sun, experts said.

Temperatures are expected to climb into the upper 90s to potentially the lower 100s in parts of Louisiana, but heat index values will be between 108 and 115 degrees due to the humidity over the weekend and potentially into next week.

The weather service on Wednesday issued a heat advisory for most of South Florida as the heat index in the area was projected to reach values from 105 to 108 degrees daily through Tuesday.

The NWS usually issues a heat advisory in a 12-hour window before the onset of extreme or dangerous heat conditions. The rule of thumb for issuing a heat advisory is typically when the maximum heat index temperature for the day is anticipated to reach 105 degrees or higher.

According to the NWS, parts of Arizona, New Mexico and Texas were expected to experience critical fire weather on Thursday and Friday.

The weather service also warned of the chance of strong thunderstorms and possible tornadoes for the southern US region.

Children play and cool off at a splash park in downtown Houston, Texas, United States, on June 15, 2023. From US south central state of Texas to southeastern Florida, about 35 million people are bracing for a widespread heat wave which is expected to last for days, the US National Weather Service (NWS) forecast on Thursday. Photo:Xinhua

People buy cold drinks at a park in downtown Houston, Texas, United States, on June 15, 2023. From US south central state of Texas to southeastern Florida, about 35 million people are bracing for a widespread heat wave which is expected to last for days, the US National Weather Service (NWS) forecast on Thursday. Photo:Xinhua

Children play and cool off at a splash park in downtown Houston, Texas, United States, on June 15, 2023. From US south central state of Texas to southeastern Florida, about 35 million people are bracing for a widespread heat wave which is expected to last for days, the US National Weather Service (NWS) forecast on Thursday. Photo:Xinhua