Coolest US Cities in Summer
Among major cities in the United States, it is San Francisco which tops the list for having the coldest weather overall in June, July and August. San Francisco's mean summer temperature is barely above 60 degrees Fahrenheit, whereas most large US cities average at least 70 degrees Fahrenheit (21 °Celsius) during summer.
The ratings below of coldest 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.
Lowest Overall Temperature
Nine major US cities have a daily mean temperature for summer that is less than 72 °F.
|City||Mean °F||Mean °C|
|San Francisco, California||61||16|
|San Jose, California||69||21|
|Buffalo, New York||70||21|
|San Diego, California||70||21|
|Rochester, New York||70||21|
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.
Coolest Summer Days
San Francisco keeps a cool average by seldom heating up over 79 °F. It typically sees just five days a year with temperatures in the 80s or 90s, and none in the 100s.
Other cities that normally don't reach 100 °F are Buffalo, Cleveland, Miami, Pittsburgh, Rochester, San Diego and Tampa. But not all of those cities have cool summer weather. Miami and Tampa spend over two-thirds of their summer days with highs in the 90s.
These large cities average fewer than ten days a summer with temperatures in the 90s
|San Diego, California||12||0|
|San Francisco, California||5||1|
|Buffalo, New York||43||3|
|Rochester, New York||49||7|
|San Jose, California||46||9|
Lowest Temperatures at Night
Nighttime temperatures in summer don't normally go below 40 °F (4 °C) at any of America's largest cities. Yet only five cities can count on every summer night cooling down to less than 71 °F (22°C): Denver, Portland, San Jose, Seattle and of course, San Francisco.
Here are the major cities that most often have summer nights when the thermometer dips into the 40s.
|Rochester, New York||9||50|
|Salt Lake City, Utah||6||31|
|Buffalo, New York||5||43|
NOAA National Centers for Environmental Information (NCEI). Climate Normals.