Houston confirms 1st heat-related death of the year amid extreme heat across US

The most populous city in Texas has confirmed its first heat-related death of the year as record high temperatures scorch a swath of the United States.

The Harris County Institute of Forensic Sciences told ABC News on Sunday that there has been one heat-related death in Houston, the only one to occur in Texas' Harris County so far this year. Victor Ramos, 67, was found in his Houston home, which didn't have air conditioning, and was taken to a local hospital where he died on June 24. The manner and cause of death were ruled to be accidental hyperthermia, according to the Harris County Institute of Forensic Sciences.

More than a dozen heat-related deaths have been recorded in Texas this year, according to a count kept by The Associated Press. At least 11 of those fatalities happened in Webb County, which includes the city of Laredo.

The news came as more than 75 million people across 13 U.S. states from California to Florida remain under heat alerts. As of Monday morning, the National Weather Service had issued excessive heat warnings for a number of cities such as Palm Springs, California; Las Vegas, Nevada; Phoenix, Arizona; and Corpus Christi, Texas. Heat advisories were issued for other cities such as Denver, Colorado; Houston, Texas; Alexandria, Louisiana; and Miami, Florida.

The extreme heat peaked in the Southwest over the weekend and was expected to drop off slightly in the coming days. But temperatures will continue to top 110 degrees Fahrenheit from Las Vegas to Phoenix.

Arizona's capital has recorded temperatures of 110 degrees and higher over the past 17 days and is on track to break the all-time-record of 18 consecutive days set in 1974. Overnight temperatures in Phoenix haven't dipped below 90 degrees for the last seven days and one more night would set a record.

El Paso, Texas, has recorded temperatures topping 100 degrees over the past 31 days, smashing the previous record of 23 consecutive days set in 1994. The El Paso Fire Department said Sunday that four people suffering from heat-related symptoms ranging from minor to severe at a car show in Ascarate Park had to be transported to a local hospital, while multiple others were checked at the scene.

Much of Texas and into the Deep South saw some respite from the dangerous combination of hot and humid weather on Sunday afternoon, with heat index values not as high as recent days. However, it was still dangerously hot for many along the Gulf Coast where temperatures were forecast to feel like 105 to 110 degrees and up.

Temperatures are forecast to return to the 100s for much of the South and the West on Monday, with highs in the 120s in Death Valley and 110 in Phoenix, Las Vegas and Palm Springs. Meanwhile, heat index values will reach the 100s across the Southeast, with up to 115 in Corpus Christi. The extreme heat is expected to continue throughout the week.

Unusually warm waters in the Gulf of Mexico and western Atlantic Ocean are contributing to the persistent and oppressive humidity and are limiting nighttime cooling, making it difficult for people in the region to find adequate relief overnight without the aid of air conditioning.

ABC News' Marilyn Heck and Vanessa Navarrete contributed to this report.