2007 North American heat wave

The major heat wave of 2007 lasted from 3 to 25 August across eastern United States, while a second wave hit the Midwest and California in October. Temperatures surpassed as far north as Kansas City, MO and St. Louis, MO. Dew points reached the mid-region of , creating heat index values of 108 or more in much of the affected areas. The accompanying high-pressure systems caused drought conditions, especially in areas that were already experiencing drought conditions, such as northern Alabama. It caused drought conditions in the Ohio and Mississippi River Valleys. The drought decreased soil moisture to below 98-99% of normal levels. A heat-wave forecast was issued in June 2007 for the Columbus, Ohio area. In Indiana, heat advisories were issued after at least four days of days in early August. In Evansville, Indiana, August had the highest average temperature recorded until that time, , surpassed in 2012. Indianapolis had a 14-day streak of temperatures of or higher. Paducah, Kentucky had 28 straight days of -plus temperatures, a record broken in 2010. North Carolina experienced temperatures over . In Charlotte, a record high of " degrees [was] set on 10 August 2007," that lasted until August 2012. Ten years later, the National Weather Service labeled the August 2007 heat wave one of the "Historic Heat Waves in the Carolinas." A new heat island was identified in Shippensburg, Pennsylvania through monitoring hourly temperatures from 27 May to 19 September 2007. In California, "a record summer heat wave" dried out tinder and led to dry conditions and fires in October 2007, causing one death and thousands of people to be evacuated. Ultimately, a disaster declaration was made by President George W. Bush. 25 people in California died that year from heat-related causes. ==Impact==

A total of 105 deaths in 2007 were attributed to the heat that year in the United States. During the heat wave itself, more than 50 deaths were reported, in addition to cases of heat exhaustion and heat stroke. During the Chicago Marathon in October, temperatures hit a record , causing dozens of hospitalizations and one death. In 2007, a total of 39 deaths were counted due to the heat from four adjoining states, Illinois, Missouri, Tennessee, and Kentucky. Over "51 deaths, including 2 in South Carolina, were attributable to this heat wave." In Birmingham, Alabama, there were 18 days with a "heat index greater than or equal to 100," lower than the index during the heat wave of 1980, while 13 heat-related deaths were attributed to the August 2007 heat wave, compared to over 100 in 1980. The fewer deaths were attributed to the increased use of air-conditioning in 2007, especially among "shut in" elderly people. ==Causes==

The heat wave was reportedly caused by several factors. First, an upper level ridge that settled over the southern plains and southeast near the Ozarks. Another cause was the troughing over the Pacific Coast and offshore Atlantic. This in turn created an Omega block pattern over the central US and caused extreme heat to build for weeks, in some cases. The ridge eventually moved back towards the west, which allowed some short-term relief for the northeastern states and Mid-Atlantic, but in the Mississippi River Valley and the southeast there remained strong heat for at least several more days. ==See also==