Call It the Summer of 100-Degree Records

This month alone, New York City hit 100 degrees for the first time since 2012. Boston reached 101. Philadelphia hit 103, Washington 102, Atlantic City 106, and Salt Lake City 109.

And that’s just the United States. Records also fell across Europe and the UK, in heat blamed for more than 1,000 deaths — and by some estimates, as many as 10,000. Reuters reported that European countries recorded over 10,000 excess deaths during the heatwave that struck western Europe in late June, according to official data, with roughly 9,000 of those deaths among people over 65. The toll underscores how disproportionately heat affects the elderly and those with preexisting conditions. Copernicus Climate Change Service data, released through the World Health Organization, showed that June 2026 was the hottest June on record for western Europe and the second-warmest globally, driven by record-high sea surface temperatures for the month. A number of experts also noted that the region’s limited use of air conditioning made the heat especially dangerous.

The US Is Getting Hotter

A paper published in PLOS Climate found that temperatures rose across much of the country between 1950 and 2021, with 84% of states reporting a mean increase. A more recent Climate Central study found that the 49 states it analyzed have warmed by an average of 2.9°F since 1970. Alaska saw the largest increase, at 4.3°F, followed by Delaware, Massachusetts, and New Jersey, each up 3.7°F.

Interestingly, the states that are already hottest aren’t warming the fastest — but among cities, the opposite is true: the hottest cities are heating up the most. Over the same period measured by Climate Central, Reno saw the largest increase at 7.8°F, followed by Las Vegas (5.9°F), El Paso (5.7°F), and Tyler, Texas (5.3°F).

Phoenix Stands Alone

Among America’s 100 largest cities by population, one stands out by far: Phoenix, the nation’s fifth-most-populous city with 1,665,481 residents as of the 2025 Census. Every year since 2000 except one (2016), Phoenix has logged more than 100 days of temperatures above 100°F. The city hit 145 such days in 2026 and 143 in 2024 — and this year, it’s already close to 70.

The Cities With the Most 100-Degree Days on Record

Climatecrisis247 reviewed data from multiple sources to identify the US cities with the most 100°F+ days on record dating back to roughly the turn of the 20th century. Official records for most of these cities begin around 1890. Sources included Fox Weather, Accuweather, Extreme Weather Watch, the National Weather Service, and NOAA. Because the starting year of measurement varies by city, the figures below are estimates.

Top Cities by Total Historical 100°F+ Days

Rank	City	Approx. Total 100°F+ Days
1	Phoenix, AZ	11,400+
2	Las Vegas, NV	~5,000–6,000
3	Dallas, TX	~2,000–2,500
4	Houston, TX	~1,000–1,500
5	San Antonio, TX	~1,500+
6	Austin, TX	~1,200+
7	Oklahoma City, OK	~1,000+
8	Tucson, AZ	~4,000+
9	El Paso, TX	~3,000+
10	Fresno, CA	~2,000+

Sources: “What Does It Take to Hit 100? The Long Road to Triple-Digit Heat in U.S. Cities”; “Historical Extreme Temperatures in Phoenix, Yuma, and El Centro.” Start dates vary by city; most NOAA and National Weather Service records begin around 1890.