Phoenix Had A Record Hottest Month For Any US City. Dozens Of Cities Also Had Their Hottest Month

P​hoenix, Arizona, had the hottest single month of any U.S. city on record, and they're just one of over a dozen cities that had their record hottest month in July.

The monthly mean temperature in July in Phoenix of 102.7 degrees was the hottest for any town or city with a year-round population of 1,000 or more anywhere in North America, according to weather.com weather historian Christopher Burt.

T​he previous record hot month for any U.S. city was 102.2 degrees in July 1996 at Lake Havasu City, Arizona, according to Brian Brettschneider, an Alaska-based climatologist.

(​CURRENT MAPS: Temperatures | Heat Indices | Dew Points)

T​he monthly mean temperature is calculated by taking the average of each day's high and low temperature. By definition, taking an average smooths out the highs and lows.

Now imagine taking an average of 62 daily high and low temperatures, and still coming out with a temperature above 100 degrees.

I​t was their first month with a mean temperature over 100 degrees, and that was over 3 degrees hotter than their previous hottest month. That's an absolute pummeling of a record in the realm of monthly temperatures.

Phoenix sweltered through their record-long 31-day streak of 110-degree-plus high temperatures, as well as a record 16-day streak in which they failed to drop below 90 degrees.

D​eath Valley had their second hottest month in July 2023 (monthly mean temperature of 107.6 degrees), just behind July 2018 (108.1 degrees).

(​MORE: Hottest Reliable Temperatures Measured On Earth)

D​ozens of U.S. cities have also had their hottest month. This wasn't just a story in Phoenix.

O​ver two dozen cities in the U.S. had their record hottest month this July.

O​ther Desert Southwest cities clocking their hottest month included Albuquerque, Las Vegas, Palm Springs and Tucson. El Paso, Texas, had its first monthly mean temperature above 90 degrees, which included a record streak of 100-degree-plus days that was three weeks longer than their previous record.

I​n the Southeast, fueled in part by very warm water, at least six Florida cities had their hottest single month. That included Ft. Myers, Key West, Miami and Tampa. Baton Rouge, Louisiana, and St. Simons Island, Georgia, also sweated through a record hot month.

W​hile the most persistent, searing heat was in the South, there were a few northern locations that also made the list.

C​aribou, Maine, had its hottest month, not necessarily because its high temperatures were off the charts. But its daily low temperatures were much warmer than usual.

(​MORE: Tracking U.S., Europe, Global Heat Records)

O​ther cities fell just short of a hottest month. From the northern Gulf Coast to Texas, eight other cities tied or set new record hot Julys, but came up a bit shy of their record hottest month.

N​ew Orleans tied its record hottest July from 2016, but was not as hot as their record hot August 2011. Austin, Texas (Camp Mabry site), has now had its two hottest Julys in the past two years, but it still wasn't as hot as August 2011, there.

T​he other cities in this hottest July, but not month bucket included Beaumont-Port Arthur, Texas; Brownsville, Texas; Corpus Christi, Texas; Victoria, Texas; Lake Charles, Louisiana; and Pensacola, Florida.

Some in the U.S. had a rather cool July, though. While the extreme heat in the Southwest and South grabbed the most attention, a rather sizable swath of the nation's mid-section had a fairly docile July, as far as heat was concerned.

A​reas from the Northern Rockies into the Northern Plains and parts of the Midwest had either an average or cooler than average July.

T​hat was because a dome of high pressure aloft responsible for the blistering heat remained camped over the Southwest U.S., and other stubborn high pressure domes were in place near Greenland and the Canadian Arctic.

T​hat forced low-pressure "troughs" to carve out of central Canada into the central U.S., ushering in occasional bouts of cooler air.

D​espite this, other massive heat waves around the world both on land and in the oceans have already clinched a new hottest month record for the planet dating to the mid-19th century.

M​ORE ON WEATHER.COM

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Jonathan Erdman is a senior meteorologist at weather.com and has been covering national and international weather since 1996. His lifelong love of meteorology began with a close encounter from a tornado as a child in Wisconsin. He studied physics at the University of Wisconsin-Madison, then completed his Master's degree working with dual-polarization radar and lightning data at Colorado State University. Extreme and bizarre weather are his favorite topics. Reach out to him on X/Twitter, Facebook and Threads. 

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