Coolest US Cities in Summer

Cool summer temperatures can be found in major cities of the United States on the west coast and in the northeast.

Among the country's 51 largest cities, San Francisco tops the list for usually having the coldest weather each day in June, July and August. San Francisco's mean summer temperature is barely above 60 degrees Fahrenheit, whereas most major US cities average at least 70 °F (21 °C) during summer.

These rankings of coldest cities use long-term temperature averages, based on weather data collected from 1981 to 2010 for the NOAA's National Climatic Data Center.

The major cities included in the 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.

US cities with the lowest normal daily mean temperatures for June, July and August
City Daily Summer Mean
°F °C
San Francisco, California 61 16
Seattle, Washington 65 18
Portland, Oregon 67 19
Rochester, New York 69 20
Buffalo, New York 69 21
San Jose, California 69 21
San Diego, California 69 21
Milwaukee, Wisconsin 70 21
Denver, Colorado 71 22
Pittsburgh, Pennsylvania 71 22
Boston, Massachusetts 71 22
Minneapolis, Minnesota 71 22
Providence, Rhode Island 71 22
Hartford, Connecticut 71 22

Coolest Summer Days

Every major US city, except Buffalo, has set a record high temperature of 100 °F (37.8 °C) or more. Still, 14 of the biggest American cities don't reach temperatures above 80 °F (27 °C) during an average summer day. Making 90 °F (27 °C) is an especially rare event in Seattle, San Diego, San Francisco and Buffalo, where it normally gets that hot on less than three days a year.

US cities with the lowest normal daily maximum temperatures for June, July and August
City Average Daily Maximum
°F °C
San Francisco, California 67 19
San Diego, California 74 23
Seattle, Washington 74 24
Buffalo, New York 78 26
Milwaukee, Wisconsin 78 26
Portland, Oregon 78 26
Boston, Massachusetts 79 26
Rochester, New York 79 26
Providence, Rhode Island 81 27
Cleveland, Ohio 81 27
Minneapolis, Minnesota 81 27
San Jose, California 81 27
Pittsburgh, Pennsylvania 81 27
Detroit, Michigan 81 27

Lowest Summer Temperatures

Nighttime temperatures don't normally drop below 40 degrees in summer at any of America's largest cities. And only rarely during June, July or August does a large US city experience freezing weather.

Temperatures in eleven of the 51 major American urban centers regularly go down below 62 °F (17 °C) during the summer. The cities most likely to have cool nights are Portland, Denver and Rochester, where temperatures of 50 °F (10 °C) or colder happen an average of 10 or 11 times a summer.

US cities having the lowest normal daily minimum temperatures for June, July and August
City Average Daily Minimum
°F °C
San Francisco, California 54 12
Portland, Oregon 55 13
Seattle, Washington 56 13
Denver, Colorado 57 14
Sacramento, California 57 14
San Jose, California 58 14
Rochester, New York 59 15
Buffalo, New York 60 16
Hartford, Connecticut 60 16
Pittsburgh, Pennsylvania 61 16
Milwaukee, Wisconsin 61 16

National Climatic Data Center. NOAA's 1981-2010 Climate Normals.

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