|Above: A group finds cooling relief at the National World War II Memorial on June 29, 2012, in Washington, D.C., during the nation’s most widespread and intense June heat wave in history. Washington’s high of 104°F broke a daily record of 101°F set almost 80 years earlier, and it fell just 2° short of the city’s all-time record high from July 20, 1930. Image credit: Yuri Gripas/AFP/GettyImages.|
For most places in the continental United States, July and August are typically the hottest months of the year and when the hottest days of the year may be expected. However, for a small portion of the Southwest (specifically southeastern Arizona, southern New Mexico, and western Texas), June is normally when the hottest daytime temperatures occur. Nevertheless, record-breaking heat waves have occurred during the month of June in every part of the country. Here is a summary of some of those historic events.
|Figure 1. A photograph of the official maximum recording thermometer at the Furnace Creek station in Death Valley, California, at the time of observation on Monday morning, July 1, 2013. This reading represents the maximum temperature for June 30. It remains the hottest reliably measured temperature in the U.S. for any month, and tied with such for the world along with a 54°C (129.2°F) observed at Mitribah, Kuwait on July 21, 2016. Image credit: NWS/Las Vegas.|
|Figure 2. Climatologist Brian Brettschneider recently wrote a blog post concerning what normally is the warmest time of the summer for the U.S. and Canada. The map above illustrates this nicely. As can be seen, only a very small part of the U.S. sees its warmest temperatures occurring during the month of June. Image credit: Courtesy Brian Brettschneider.|
The warmest June nationally on record (average monthly temperature) for the entire contiguous U.S. was that of June 2016. The runner-ups were those of 1933, 2015, 1918, and 1994, based on data beginning in 1895.
|Figure 3. Average June temperatures for the contiguous U.S. since 1895. The Dust Bowl era of the 1930s featured some of the warmest Junes on record, as have some recent years, most notably the Junes of 2015 and 2016. Graph from NOAA/NCEI Climate at a Glance.|
|Figure 4. Warmest June on record for each of the nine climate regions defined for the contiguous U.S. by NOAA’s National Centers for Environmental Information.|
Although the above may have been the warmest Junes on record for these respective regions, those years are not when the most intense June heat waves took place (with the exception of June 2015 in the West and Northwest regions).
Notable June heat waves
Remarkable June heat waves struck one part of the country or another in the years 1930, 1933, 1934, 1936, 1952, 1954, 1966, 1988, 1990, 1994, 2012, 2015, and 2017, just to list a few. But the most widespread and intense June heat wave in modern U.S. history was that of 2012, when many monthly heat records for June (and many all-time local records for any month) were smashed from Montana south to Kansas and east to Georgia, the Carolinas, and Virginia. (Amazingly, one of the nation’s most anomalous heat waves on record had occurred just three months earlier, in March 2012.) The apex of the June heat wave affected the West and Plains between June 22 and 27 and the Southeast from June 28 to 30. Here are some of the highlights.
The single most impressive record set in Colorado during this heat wave was the 114°F measured at Las Animas on June 23. This tied the hottest temperature ever measured during any month anywhere in the entire state of Colorado; 114° has been recorded in the past at Las Animas on July 1, 1933, and Sedgwick on July 11, 1954.
All-time heat records (for any month) were also set or tied in Denver with 105° on both June 25 and June 26 (tied with 105° on July 20, 2005 and Aug. 8, 1878) and Colorado Springs with 101° on June 26 (previous record of 100° set on five previous occasions including June 24 and June 25, 2012). Lamar hit 112° on June 27 (previous record 111° on July 13, 1934 and also on June 26, 2012). In far northeastern Colorado, all-time heat records were set at Yuma (111°) and Holyoke (110°) on June 27.
Denver reached at least 100° on a record-tying five consecutive days, June 22-26. Pueblo recorded six consecutive days of 105° or hotter on June 22-27, its longest streak of such heat. Pueblo’s maximum during this heat wave was 107° on June 24th, two degrees short of its all-time high of 109° and one degree short of its June record of 108° (set on June 29, 1990).
Dodge City recorded its all-time high of 111° on June 27th (previous record of 110° set on three previous occasions, including June 26, 2011, and June 26, 2012). This is a particularly significant measurement since Dodge City has one of the longest continuous periods of record in the U.S., going back to September 1874. Norton Dam reached 118°, a new Kansas state record for the month of June.
A Nebraska monthly heat record for June was set at Beaver City with 116° on June 28th (previous record was 114° at Franklin on June 26, 1936). On the same day, three other Nebraska locations set all-time records: McCook with 115°, Benkelman with 114°. and Sidney with 111°.
An all-time heat record was set at Miles City with 111° on June 26. However, this reading was made at the airport (period of record 1937-current), whereas a temperature of 113° was recorded at the Miles City COOP downtown site on July 20, 1960 (POR 1893-1982). In any case, the 111° was just one degree short of Montana’s monthly June heat record (112° at Baker on June 28, 2002, and also at Wolf Point on June 26, 1988).
The excessive heat of June 2012 affected only the northeastern third of New Mexico. Santa Fe (99° on June 23) and Tucumcari (108° on June 27) both came within 1° of their respective all-time records. This was a June record for Tucumcari, but Santa Fe had already seen 100° on June 5, 2010.
|Figure 5. Maximum and minimum temperatures for select stations on June 26, 2012. An interesting fact that exemplifies the magnitude of the Pacific trough and plains ridge is that it was snowing in the mountains along the border of Idaho and Montana above 7000 feet at the same time it was 111° in Miles City, Montana. Image credit: NOAA/NWS/WPC.|
By the end of the month the heat dome had drifted over the Southeast, resulting in yet another slew of all-time heat records. Here’s a summary of the highlights in the Southeast and Ohio Valley:
109° at Kakaskia River Navigation Lock near Cairo on June 29 broke the all-time record for the Cairo area (old record 106° on August 9, 1930) and also surpassed the state’s June record of 108° at Palestine, set most recently on June 26, 1954.
106° was measured at Fort Wayne, Indiana on June 28, tying the all-time record set on July 14, 1936.
Paducah recorded 108° on June 29th, an official all-time record (although a previous site in Paducah measured 112° in July 1930). Nolan River Lake reached 111° on June 30, a new monthly record for Kentucky (surpassing the 110° set during the June heat wave of 1936). All-time heat records were broken at Jackson (104°) and London (105°), but these sites have short periods of record.
This was the most intense heat event in Tennessee state history, at least for the eastern two-thirds of the state. All-time records were achieved at the following sites that have significant POR’s (periods of record):
109° Nashville on June 29th (old record 107° on 7/28/1952)}
107° Chattanooga on June 30th and July 1st (old record 106° on 6/29/2012 and 7/28/1952)
105° Knoxville on June 30th and July 1st (old record 104° on 7/12/1930)
103° Bristol on June 30th (old record 102° 7/28/1952)
A reading of 110° was reported at three sites on the 29th and 30th (see state table below for locations), all being new June records for the state of Tennessee.
As with Tennessee, this was one of the greatest heat events in Georgia state history. The following all-time records were tied or broken:
109° Athens on June 29th (old record 108° on 7/12/1930)
108° Macon on June 30th (ties same on 7/17/1980)
106° Atlanta on June 30th (old record 105° on 7/17/1980)
106° Columbus on June 30th (ties same on 9/5/1925)
The Athens reading of 109° tied the June monthly record for the state of Georgia (the reported temperature of 110° set at Warrenton in June 1959 is not reliable).
This was almost certainly the most intense heat wave in South Carolina records. All-time heat records included:
109° Columbia on June 29th and 30th (old record 107° on multiple occasions).
107° Greenville on July 1st (old record 105° set on June 29, 2012 and August 10, 2007, although 106° was recorded by the Army Signal Corps on July 18, 1887).
The temperature reached 113° at Columbia State University on the 29th, the hottest temperature ever measured for any month in the state of South Carolina (the previous record being 111° at Camden on June 28, 1954).
All-time heat records were tied or broken at:
105° Raleigh on June 29th and 30th (ties previous record set on 8/21/2007 and 8/18/1988)
104° Charlotte on June 29th and 30th (ties same on August 9, 2007, August 10, 2007, and September 6, 1954).
The state’s June heat record of 107° was tied at Hamlet on June 29.
VIRGINIA AND WASHINGTON D.C.
The 104° at National Airport in D.C. on June 29 (see photo at top) was a new June record for the D.C. area and fell just 2° short of the all-time record of 106° set on July 20, 1930.
107° near Walkerton (two miles northwest) on June 29 was a new state heat record for June.
|Figure 6. Maximum and minimum temperatures recorded across the U.S. on June 29, 2012, when many all-time heat records were set in the Southeast. Image credit: NOAA/NWS/WPC.|
The Northwest heat wave of June 2015
June 2015 was by far the warmest June on record for virtually every site in Washington, Oregon, Idaho, northern California, and portions of Nevada and Utah.
The heat peaked at the end of the month with new June heat records set at Walla Walla, WA (113° on June 28), also breaking the Washington state June monthly record along with two other locations); 112° at Pilot Rock, OR (which tied that state’s June monthly record); and 114° at Glenns Ferry, ID, a new Idaho record for any June. An unofficial reading of 116° was reported from Pittsburg Landing in the Snake River Canyon as well. Boise hit 110° on the 28th, 1° short of their all-time record (111° on July 19, 1960).
|Figure 7. Temperature anomalies for the U.S. during June 2015 (above), followed by a table of records set at various sites in the Northwest and West for June monthly average temperature. Note how some sites (like Yakima, Washington) surpassed their previous warmest June month by more than 4°!|
The Southwest heat wave of June 1994
The most intense heat wave to punish the already hot deserts of the Southwest occurred in late June 1994. Arizona saw its all-time hottest temperature with a 128° reading at Lake Havasu on the 29th (although this reading is disputed). Nevada also set its all-time heat record with a 125° reading at Laughlin the same day, and New Mexico did the same with a 122° reading at the Waste Isolation Pilot Plant on June 27 (the latter is also a disputed reading, but a bona fide reading of 118° at Ochoa would still rank as the hottest temperature ever measured in the state). Monahans tied the Texas all-time heat record with a 120° reading on June 28. A reading of 120° at Tipton, Oklahoma was reported (which would also tie that state’s warmest reading on record), but this figure is also disputed.
Some of the larger towns and cities that broke their all-time heat records include Albuquerque, NM, with 107°; Roswell, NM, with 114°; Midland, TX, with 116°; Lubbock, TX, with 114°; and El Paso, TX, with 114°. The heat wave was unrelenting in El Paso where eight consecutive days of record high temperatures (all of which still stand) occurred from June 25 through July 2. This is truly a remarkable stretch of record-breaking heat when the period of record back to 1887 is considered. The nights offered no relief: the minimum temperatures of 85° set on July 1 and July 3 remain the warmest on record for the city.
Heat Wave of June 1966: The Northeast and elsewhere
Record-breaking heat waves (so far as matching or breaking all-time records is concerned) are very rare if nonexistent for the Northeast and Upper Midwest in June, since the heat normally doesn’t really crank up there until July. However, Vermont and New Hampshire experienced a truly anomalous heat wave early in June 1919. Temperatures peaked at 101° in St. Johnsbury, VT, on June 4 and 5, and 102° at Durham and Franklin, NH, on June 3 and 5, respectively.
A late June heat wave in 1966 heralded what would become a true record-breaker in the first week of July that year in the Northeast. The Central Park site in New York City tied its all-time June record high of 101° on June 27, also recorded on June 29, 1934. In fact, the Junes of 1934 and 1936 both experienced intense heat waves not just in the Northeast but also in the Upper Midwest and all points south. All-time June state heat records were set in 1936 in Arkansas (113°), Indiana (111°), Louisiana (110°), Mississippi (111°), and Missouri (112°).
In the Upper Midwest, a late May heat wave in 1934 spilled over into early June, resulting in a monthly heat record for Wisconsin with 106° readings in Racine and Brodhead on June 1 and 2, respectively.
Below is a table detailing each state’s all-time hottest reading for June.
Christopher C. Burt
KUDOS: Thanks to Brian Brettschneider for reproduction of his map and Mark Stroud (Moon Street Cartography) for producing the table of state monthly heat records. Thanks also to Howard Rainford for research on the state monthly temperature records.
|Figure 8. The hottest single temperature (in degrees F) recorded in each U.S. state during the month of June.|