Phoenix hits record October highs during heat wave before wrapping up its warm season

PHOENIX — Phoenix wrapped up its annual six-month warm season this week after the Southwest broiled through an unprecedented autumn heat wave that saw daily highs in the United States' hottest city topping 110 degrees Fahrenheit (43.3 Celsius) in October for the first time on record — four times during the month so far.

The National Weather Service said the heat wave that stretched into October saw Phoenix set an annual record of 70 days with highs reaching or passing 110 F. Sept. 19, 2010, previously was the latest date in the year Phoenix had recorded temperatures that high.

“We are now done with the extreme weather, but we may not necessarily be done with the records for the year,” said Sean Benedict, weather service lead meteorologist in Phoenix. “We are cooling off right now, but we do have a forecast of 100 degrees next Thursday.”

“Whew, that should hopefully end the latest round of high max temp records,” the Arizona State Climate Office said on the social platform X. “Phoenix had 19 new records and 2 ties. Tucson had 18 new records and no ties. Flagstaff had 10 new records and 1 tie. A lot of the new records were set by several degrees.”

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

Maricopa County public health officials say that 389 heat-related deaths have been confirmed so far this year, with another 292 deaths being investigated for possible heat causes. Officials recorded 645 heat-related deaths last year in the county of some 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 state, 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 determined that heat was a factor in at least 402 deaths as of mid-October.

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

The University of New Mexico's Office of the Medical Investigator over the past two years has been grappling with a tenfold increase in presumed migrant deaths near the U.S.-Mexico border, a majority of them from heat-related causes.