The Warmest Day of the Year in The United States
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We tend to connect “summer” with “hot” due to obvious reasons. For most of the U.S., the warmest conditions during the meteorological summer months in the Northern Hemisphere (June, July, and August) are observed. However, it is worth noting that the “hottest day of the year” from a climatological perspective differs significantly throughout the United States. Its occurrence can range from early June in certain regions to as late as September and October in others!
To help you identify the hottest time of year in your region, NCEI has collaborated with NOAA Climate.gov to create “Warmest Day of the Year” maps for the United States.
The maps are based on NCEI’s 30-year averages of climatological variables, including average high temperatures by day, derived from its 1991–2020 U.S. Climate Normals. Scientists can identify the warmest day of the year by analyzing these smoothed values and determining the day with the highest maximum temperature normal.
Even though the highest amount of solar radiation reaches Earth during the summer solstice on June 21 in the Northern Hemisphere, temperatures in the United States usually continue to rise throughout July. After the solstice, temperatures rise because the sun’s heat input during the day remains greater than the cooling at night for several weeks, until the temperatures start to decrease in and of July and August. However, this isn’t the case everywhere! Climate in the United States can be very variable, as shown by the “Warmest Day of the Year” maps.
As an example, June values in New Mexico, Arizona, and Texas reflect the impact of North American Monsoon, which causes an increase in rainfall in the Southwest of the United States. As these areas tend to be cloudier and wetter from July through September, June is, on average, the warmest month. For instance, the warmest day of the year in Terlingua, Texas, is 11th of June.
On the Pacific Coast, the marine layer tends to stick around, causing cool temperatures in the beginning of summer. The warmest days, on average, happen in October. In reality, daily high temperature normals in San Francisco peak (California) on October 2nd.
The Hottest Temperatures Recorded In U.S. States
The highest temperature ever recorded in the United States was 134°F (56.7°C), which was recorded at Greenland Ranch (now Furnace Creek) in Death Valley, California, on July 10, 1913.
Here are the highest temperature records for each U.S. state and territory in the United States:
| Rank | State/Territory | Highest Temperature | Date | Location |
|---|---|---|---|---|
| 1 | California | 134°F (56.7°C) | July 10, 1913 | Death Valley |
| 2 | Arizona | 128°F (53.3°C) | June 29, 1994 | Lake Havasu City |
| 3 | Nevada | 125°F (51.7°C) | June 29, 1994 | Laughlin |
| 4 | New Mexico | 122°F (50°C) | June 27, 1994 | Waste Isolation Pilot Plant |
| 5 | Kansas | 121°F (49.4°C) | July 24, 1936 | Alton |
| 6 | North Dakota | 121°F (49.4°C) | July 6, 1936 | Steele |
| 7 | Arkansas | 120°F (48.9°C) | August 10, 1936 | Ozark |
| 8 | Oklahoma | 120°F (48.9°C) | July 18, 1936 | Tipton |
| 9 | South Dakota | 120°F (48.9°C) | July 5, 1936 | Gann Valley |
| 10 | Texas | 120°F (48.9°C) | August 12, 1936 | Seymour |
| 11 | Colorado | 118°F (47.8°C) | July 11, 1888 | Bennett |
| 12 | Idaho | 118°F (47.8°C) | July 28, 1934 | Orofino |
| 13 | Iowa | 118°F (47.8°C) | July 20, 1934 | Keokuk |
| 14 | Missouri | 118°F (47.8°C) | July 14, 1954 | Warsaw and Union |
| 15 | Nebraska | 118°F (47.8°C) | July 24, 1936 | Minden |
| 16 | Washington | 118°F (47.8°C) | August 5, 1961 | Ice Harbor Dam |
| 17 | Illinois | 117°F (47.2°C) | July 14, 1954 | East St. Louis |
| 18 | Montana | 117°F (47.2°C) | July 5, 1937 | Medicine Lake |
| 19 | Oregon | 117°F (47.2°C) | July 27, 1939 | Pendleton |
| 20 | Utah | 117°F (47.2°C) | July 5, 1985 | St. George |
| 21 | Indiana | 116°F (46.7°C) | July 14, 1936 | Collegeville and New Albany |
| 22 | Mississippi | 115°F (46.1°C) | July 29, 1930 | Holly Springs |
| 23 | Wyoming | 115°F (46.1°C) | August 8, 1983 | Basin |
| 24 | Kentucky | 114°F (45.6°C) | July 28, 1930 | Greensburg |
| 25 | Louisiana | 114°F (45.6°C) | August 10, 1936 | Plain Dealing |
| 26 | Minnesota | 114°F (45.6°C) | July 29, 1917 | Beardsley |
| 27 | Wisconsin | 114°F (45.6°C) | July 13, 1936 | Wisconsin Dells |
| 28 | Ohio | 113°F (45°C) | July 21, 1934 | Gallipolis |
| 29 | South Carolina | 113°F (45°C) | June 28, 1954 | Camden |
| 30 | Tennessee | 113°F (45°C) | August 9, 1930 | Perryville |
| 31 | Alabama | 112°F (44.4°C) | September 5, 1925 | Centerville |
| 32 | Georgia | 112°F (44.4°C) | August 20, 1983 | Greenville |
| 33 | Michigan | 112°F (44.4°C) | July 13, 1936 | Mio |
| 34 | West Virginia | 112°F (44.4°C) | July 10, 1936 | Martinsburg |
| 35 | Pennsylvania | 111°F (43.9°C) | July 10, 1936 | Phoenixville |
| 36 | Delaware | 110°F (43.3°C) | July 21, 1930 | Millsboro |
| 37 | New Jersey | 110°F (43.3°C) | July 10, 1936 | Runyon |
| 38 | North Carolina | 110°F (43.3°C) | August 21, 1983 | Fayetteville |
| 39 | Virginia | 110°F (43.3°C) | July 15, 1954 | Balcony Falls |
| 40 | Florida | 109°F (42.8°C) | June 29, 1931 | Monticello |
| 41 | Maryland | 109°F (42.8°C) | July 10, 1936 | Cumberland |
| 42 | New York | 108°F (42.2°C) | July 22, 1926 | Troy |
| 43 | Massachusetts | 107°F (41.7°C) | August 2, 1975 | Chester |
| 44 | Connecticut | 106°F (41.1°C) | July 15, 1995 | Danbury |
| 45 | New Hampshire | 106°F (41.1°C) | July 4, 1911 | Nashua |
| 46 | Maine | 105°F (40.6°C) | July 10, 1911 | North Bridgton |
| 47 | Vermont | 105°F (40.6°C) | July 4, 1911 | Vernon |
| 48 | Rhode Island | 104°F (40°C) | August 2, 1975 | Providence |
| 49 | Alaska | 100°F (37.8°C) | June 27, 1915 | Fort Yukon |
| 50 | Hawaii | 100°F (37.8°C) | April 27, 1931 | Pahala |
Thus, in most states, the highest temperature records were registered in July.
| Month | States |
|---|---|
| April | Hawaii |
| June | Arizona, Alaska, Florida, Nevada, New Mexico, South Carolina |
| July | California, Colorado, Connecticut, Delaware, Idaho, Indiana, Illinois, Iowa, Kansas, Kentucky, Maine, Maryland, Michigan, Minnesota, Missouri, Mississippi, Montana, Nebraska, New Hampshire, New Jersey, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, South Dakota, Utah, West Virginia, Vermont, Virginia, Wisconsin |
| August | Arkansas, Georgia, Louisiana, Massachusetts, North Carolina, Rhode Island, Tennessee, Texas, Washington, Wyoming |
| September | Alabama |
