Maximum and minimum temperatures recorded across the U.S. on 29 June 2012. Map from Daily Weather Maps and NOAA via wunderground.com

By Christopher C. Burt
1 July 2012 After scorching portions of the West and Plains early last week, the amazing heat wave of June 2012 slid eastward on Thursday, June 28, continuing to astonish us with more all-time heat records. Below is a summary of those. […] ALL-TIME HEAT RECORDS BROKEN OR TIED JUNE 28-30 There is no point in listing or even attempting to summarize all of the June monthly records set in the region from Missouri to Maryland and south to Georgia during the June 28-30 period. The 108° in St. Louis on June 28th was perhaps the most significant of those. What was truly astonishing was the number of all-time any month records that were broken or tied. This is especially extraordinary since they have occurred in June rather than July or August when 95% of the previous all-time heat records have been set for this part of the country (unlike the Southwest where June is often the month that all-time heat extremes are recorded).
ILLINOIS 109° at Cairo Airport on June 29th broke the all-time record for Cairo (old record 106° on 9 August 1930) and also surpasses Illinois’ June state record of 108° at Palestine in June 1954. Chicago reached 100° at both O’Hare and Midway Airports on June 28th, the first 100° reading for either site since 2005. As of July 1st Chicago O’Hare has experienced 18 90°+ days so far this year, the most on record at this point in the season and about what the average number of such days is for an entire year. INDIANA 106° was measured at Fort Wayne, Indiana on June 28 (tying the all-time record set on 7/14/1936). KENTUCKY Paducah recorded 108° on June 29th, an all-time official record (although a previous site in Paducah measured 112° in July 1930). Bowling Green hit 109° on June 29th, short by 1° of Kentucky’s all-time state June record of 110° at St. John’s Academy in June 1936. All-time heat records were broken at Jackson (104°) and London (105°), but these sites have short periods of record. TENNESSEE This has been 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) GEORGIA Again, this was one of the hottest events in Georgia state history. The following all-time (any month) 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) […] SOUTH CAROLINA This was almost certainly the most intense heat wave in South Carolina’s history. Here’s the run down (all-time any month heat records): 109° Columbia on June 29th and 30th (old record 107° on multiple occasions). 107° Greenville on July 1st (old record 105° set on 6/29/2012 and 8/10/2007, although 106° was recorded by the Army Signal Corps on 18 July 1887). Temperatures of 113° were reported from Johnston and the University of South Carolina site in Columbia on June 29th. If verified, these would establish a new all-time state heat record for any month at any location (current record being 111° at Camden on 28 June 1954). NORTH CAROLINA All-time heat records tied or broken: 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 8/9/2007, 8/10/2007, and 9/6/1954). Southern Pines reported a temperature of 108° on June 30th. If verified, this would be a new June state heat record beating the 107° reported from Lake Mitchie in June 1959 but short 2° of a suspicious reading of 110° at Fayetteville on 21 August 1983. There appears to be no data to support the figure from Fayetteville in 1983. The hottest indisputable record for North Carolina is 109° at Weldon on 7 September 1954. […]

The Amazing June Heat Wave of 2012 Part 2: The Midwest and Southeast June 28-30