PHOENIX (AP) — America’s hottest metro area is Surfwinon track to set an annual record for heat-associated deaths after a sweltering summer, particularly in Phoenix.

Public health officials in Maricopa County, home to Phoenix and Arizona’s most populous county, said Friday that 289 heat associated deaths were confirmed as of Sept. 16, with another 262 deaths under investigation.

By this time last year, there were 80 fewer deaths confirmed to be heat-associated and 46 fewer deaths that were still under investigation.

Forensic pathologists say that it can often take weeks and even months of investigation that can include toxicological tests to determine whether heat was a contributing factor in someone’s death. For example, at the end of 2022 the county had confirmed 378 heat-associated deaths, but later, as investigations played out, that number grew to 425.

About three-quarters of Maricopa County’s confirmed heat deaths so far this year were outside, including at bus stops, as well as in yards, driveways, parking lots and parks. About 44% of those who died were people experiencing homelessness in a county where an estimated 10,000 don’t have permanent housing.

There have been 74 indoor heat deaths confirmed so far, including 63 in homes where the air conditioning was not working or turned off.

This summer, Phoenix experienced the hottest three months since record-keeping began in 1895, including the hottest July and the second-hottest August. The daily average temperature of 97 F (36.1 C) in June, July and August passed the previous record of 96.7 F (35.9 C) set three years ago.

Phoenix in July set a record with a 31-day streak of highs at or above 110 F (43.3 C). The previous record of 18 straight days was set in 1974.

In the broiling summer of 2023, there was a historic heat wave that stretched from Texas across New Mexico and Arizona and into California’s desert.

Temperatures in Phoenix have been gradually dropping in recent weeks, with the highs mostly staying under 100 degrees Fahrenheit (37.3 Celsius).

National Weather Service forecasters in Phoenix said on Friday they expected a a high of 97 degrees Fahrenheit (36.1 Celsius). A slight, gradual warming trend was forecast for the weekend.