Still Dreaming of Retirement in the Sun Belt?

In 2015, when Diana and Charles Cox were considering where to retire, they drove their R.V. across the Southwest to visit several possibilities: Santa Fe, Sedona, Phoenix, Las Vegas.

They’d lived in San Jose, Calif., for nearly 20 years, but Ms. Cox was winding down her practice as a biotech patent attorney, and her income was dropping as taxes, housing and other living costs were rising.

Her husband, 71, a contractor, had retired years earlier. “I was having more and more trouble paying the mortgage,” said Ms. Cox, who is 69.

Phoenix won out because of its lower costs, international airport and many health care providers, essential for two people with chronic medical conditions. The couple bought a house in a 55-plus community in suburban Goodyear, Ariz., in 2016. Knowing the summer heat there would be intense, they planned to spend the season back in the Bay Area in their R.V.

But the pandemic made travel feel unsafe for years. Mr. Cox underwent treatment for prostate cancer. Ms. Cox’s father moved in and needed care. So they have mostly summered in Goodyear.

The number of older Americans like the Coxes who are exposed to extreme heat is increasing, the result of an aging population, continuing migration to heat-prone places and climate change. Researchers say the trend will only get worse.