Hottest US Cities in Summer

Among the largest cities in the United States, Phoenix and Las Vegas stand out as consistently having remarkably hot weather during the months of June, July and August. This is most apparent in the number of days they endure with highs in the 100s Fahrenheit (over 37 degrees Celsius). The data here look at several different temperature measures of the US cities with the hottest summertime weather.

These ratings of hottest cities use long-term temperature averages for the three summer months, June, July and August, based on weather data collected from 1991 to 2020 for the US National Centers for Environmental Information. The major cities included in these weather rankings represent the 51 metropolitan areas in the United States with the most people, all those with over one million residents in 2010, according to the US Census Bureau.

Highest Summer Temperature Overall

Phoenix and Las Vegas are the two major cities with an average temperature throughout summer that's above 90 degrees Fahrenheit (32 °Celsius). Another ten US cities have average summer temperatures in the 80s.

US cities with the highest normal daily mean temperatures in June, July and August
City Mean °F Mean °C
Phoenix, Arizona 94 34
Las Vegas, Nevada 91 33
Dallas, Texas 86 30
Austin, Texas 85 30
San Antonio, Texas 84 29
Houston, Texas 84 29
Miami, Florida 84 29
Tampa, Florida 84 29
New Orleans, Louisiana 83 29
Jacksonville, Florida 83 28
Orlando, Florida 83 28
Memphis, Tennessee 82 28

City links take you to more detailed information on temperatures for that location. You can also view a summary of temperature averages for all major US cities and city temperatures in recent years and a complete list of America's 51 largest urban centers.

Hottest Summer Days

Only at Phoenix and Las Vegas do highs in the 100s F occur on most summer days. For the other dozen cities that exerience high temperatures on at least two-thirds of summer days, the thermometer more commonly heats up into the 90s. But not all cities that frequently have 90-degree weather can expect temperatures topping 100 each year. In Florida and Louisiana, several hot cities don't experience 100-degree weather.

These 14 major cities most often have temperatures reaching 90 °F during summer.

Number of days in summer when the temperature climbs to at least 90 or 100 °F
City 90 °F
32 °C
100 °F
38 °C
Phoenix, Arizona 91 80
Las Vegas, Nevada 88 67
Austin, Texas 82 26
San Antonio, Texas 81 16
Dallas, Texas 79 20
Houston, Texas 73 3
Orlando, Florida 71 0
Jacksonville, Florida 67 2
New Orleans, Louisiana 64 0
Miami, Florida 64 0
Sacramento, California 62 19
Riverside, California 61 14
Tampa, Florida 61 0
Oklahoma City, Oklahoma 60 12

Warmest Cities at Night

A few American cities don't often cool down much at night during summer. Miami can expect every night during summer to remain above 70 degrees. Overall though, Phoenix has the hottest nights, which average above 80 °F for the season.

For the eleven cities listed below, nighttime temperatures stay above 70 degrees on all but a handful of nights in summer. All other major US cities usually see 27 or more nights a summer when it cools off to below 70.

Number of nights during summer when the temperature drops to 70 °F or below
City 70 °F
21 °C
Miami, Florida 0
Tampa, Florida 2
Phoenix, Arizona 2
Orlando, Florida 3
Houston, Texas 3
Jacksonville, Florida 4
New Orleans, Louisiana 6
Las Vegas, Nevada 8
San Antonio, Texas 10
Dallas, Texas 10
Reference

NOAA National Centers for Environmental Information (NCEI). Climate Normals.

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