The hottest cities in the US are no strangers to triple-digit temperatures, but new data on mortality and air quality suggests the risks extend well beyond discomfort for visitors and residents alike. From Phoenix, Arizona, to Brownsville, Texas, a cluster of Sun Belt cities regularly endures conditions that test the limits of habitability, and the trade and tourism industries serving them are increasingly required to factor that reality into their planning.
Phoenix Leads the Hottest Cities in the US, and the Health Data
Phoenix, Arizona, records an average summer temperature of 93.7°F and a record high of 122°F, placing it at the top of any ranking of the hottest cities in the US. Yet the city is simultaneously one of the fastest-growing in Arizona, creating a tension that planners and the hospitality sector cannot ignore. The urban density compounds the problem: stretches of concrete radiate stored heat through the night, with overnight temperatures regularly staying above 90°F.
The human cost is documented. According to ClimateCheck, more than 150 people died from the effects of heat waves in Phoenix across 2016, 2017 and 2018 combined. That toll sits alongside a separate air-quality concern: in 2025, the American Lung Association ranked Phoenix the fourth most ozone-polluted metropolitan area in the country, according to The Nature Conservancy. For hoteliers, ground operators and inbound tour companies routing visitors through the city, the combination of extreme heat and poor air quality in summer months represents a material factor in product design and risk communication.
The Nature Conservancy also notes that the number of days above 110°F in Arizona cities is expected to more than double by 2060. That trajectory has already prompted speculation, noted in the source material, that Phoenix and other cities on this list may eventually become too hot to sustain permanent populations at current scale.
Winter, by contrast, remains Phoenix’s commercial sweet spot for leisure travel. Temperatures settle into the low 80s when much of the country is under snow, drawing snowbirds and resort guests. By late winter, desert vegetation begins to bloom, adding another draw for operators building itineraries around the Sonoran Desert.
Yuma and Las Vegas: Extreme Heat with Different Risk Profiles
Yuma, Arizona, holds the highest recorded temperature of any city in the US at 124°F, set in 1995, and has been recognised by the World Meteorological Organization as the sunniest city on Earth. The city receives around 91% of possible sunlight hours, exceeding 4,000 hours of sun per year. Surrounding farmland adds an evaporation effect that can push humidity (and the perceived temperature) above 120°F in summer. Snowbird traffic fills the gap, with November through March delivering mid-70s daytime temperatures and recreational demand on the Colorado River.
Las Vegas, Nevada, the only city outside Texas and Arizona in the top ten, sees summer temperatures ranging between 105°F and 110°F with some of the lowest humidity in the country. The city has responded structurally: it recycles nearly 100% of all indoor water used along The Strip, returning it to Lake Mead. Spring and autumn remain the most commercially viable periods for leisure product, with comfortable daytime temperatures and access to nearby attractions.
Texas Cities Dominate the Mid-Tier Rankings
Seven of the ten hottest cities in the US are in Texas, with humidity the defining variable rather than raw temperature in most cases. San Antonio posts an average summer temperature of 85.4°F, but a heat index running 10–15°F above the thermometer reading means it can feel like 105°F for days at a time, with overnight temperatures rarely dipping below 78°F. McAllen carries the highest average annual temperature of any city at 77.4°F, driven by elevated overnight temperatures and a moderate winter that avoids the desert dip experienced elsewhere.
Laredo differs from its Texas peers in that its heat is driven by dry inland winds off the northern Mexican plateau rather than humidity, with raw temperatures exceeding 102°F for extended stretches. Its record high of 115°F has been matched on multiple occasions, most recently in 2023. Brownsville, meanwhile, regularly records dew points of 78°F–80°F, capable of making an 86°F day feel closer to 110°F and suppressing overnight cooling entirely.
For travel operators building product around any of these markets, the window of comfortable conditions is consistent: October through April covers most of the Texas Gulf Coast cities, with spring events such as Fiesta San Antonio and South by Southwest in Austin anchoring leisure itineraries at either end of the viable season.
The City of Phoenix and its peer Sun Belt destinations will remain major volume markets for the US inbound and domestic sectors regardless of summer conditions. The data now emerging on heat mortality and air quality, however, signals that operators have a growing duty-of-care obligation to communicate seasonal risk clearly to travellers booking into these cities during peak summer months.
