The 2007 North American heat wave started at the end of July and lasted into the first weeks of August.
Dew points reached the mid-region of 70 °F (21.1 °C), creating heat index values of 108 or more in much of the affected areas.
"[2] "Temperatures soared well into the 90s and 100s°F across almost all of North and South Carolina for three solid weeks, with all-time records for heat tied or broken in a number of locations," the NWS reported.
[15][16] During the Chicago Marathon in October, temperatures hit a record 88 °F (31.1 °C), causing dozens of hospitalizations and one death.
[17] In 2007, a total of 39 deaths were counted due to the heat from four adjoining states, Illinois, Missouri, Tennessee, and Kentucky.
[15] In Philadelphia, the Pennsylvania Medical Society issued a health warning about the dangers and treatment of heat stroke.
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.