PHOENIX (AP) — Phoenix ended its annual six-month warm season this week after the Southwest experienced an unprecedented fall heat wave that saw daily highs of over 110 degrees Fahrenheit (43.3 Celsius) in October in the hottest city in the United States For the first time since records began – four times so far during the month.

The National Weather Service said the heat wave, which lasted into October, caused Phoenix to set or exceed an annual record of 70 days with high temperatures as high as 110 F. September 19, 2010 was the last date in the year that Phoenix recorded such high temperatures.

“We're done with the extreme weather now, but we may not be done with the records for the year,” said Sean Benedict, chief meteorologist for the weather service in Phoenix. “We’re starting to cool down, but we have a forecast of 100 degrees next Thursday.”

“Phew, that should hopefully end the final round of high temperature records,” the Arizona State Climate Office said on the social platform X. “Phoenix had 19 new records and two ties. Tucson had 18 new records and no ties. Flagstaff had 10 new records and 1 tie. Many of the new records were set by several degrees.”

The high temperature in Phoenix on Friday was expected to reach 79 F (26.1 C), with cooler temperatures continuing through the weekend and into next week.

Maricopa County public health officials say 389 heat-related deaths have been confirmed so far this year and an additional 292 deaths are being investigated for possible heat causes. Officials recorded 645 heat-related deaths last year in the county of about 4.5 million people, which includes Phoenix.

The Medical Examiner's Office in Arizona's Pima County, home to Tucson, the state's second most populous, reported that there have been 131 heat-related deaths so far this year.

The Office of the Coroner/Medical Examiner in Nevada's Clark County said it has determined that heat played a role in at least 402 deaths through mid-October.

The published number of heat-related deaths in New Mexico is three months behind this year, so it doesn't take into account the hottest months of the year. But the number of cases of heat-related illnesses reported from emergency rooms across the state this year stood at 957 as of Friday.

The University of New Mexico's Office of the Medical Investigator has grappled with a tenfold increase in suspected migrant deaths near the U.S.-Mexico border over the past two years, most of which were attributed to heat-related causes.