Meteorology
Temperatures hit 118 °F (48 °C) on July 21 in Phoenix, making it the hottest day since 1995 and one of the 11 hottest since 1895, when temperature records were first kept in the city. California temperatures began reaching record levels by July 22. In one section of the City of Los Angeles, Woodland Hills, the temperature reached 119 °F (49 °C) making it the highest recorded temperature in the county and within the city border breaking the old record of 118 in Canoga Park. The unusual daytime heat resulted in extremely high overnight temperatures. Needles, California recorded a low temperature for Sunday, July 23 at 5 am., of 100 °F and in the LA basin the same night, Burbank recorded an overnight low of 77 °F (25 °C).
The California heat wave broke local records. According to some reports it was "hotter for longer than ever before, and the weather patterns that caused the scorching temperatures were positively freakish." Fresno, in the central California valley, had six consecutive days of 110 degree-plus Fahrenheit temperatures.
Beginning July 31 and into early August, the Midwest, Ontario, and Atlantic states also began experiencing the heat. Temperatures approached the 100 mark in Rochester, New York on August 1 and were coupled with the highest humidity the area has experienced in over 51 years. The heat index reached 110 °F that day. La Guardia Airport in New York City recorded three consecutive days above 100 °F. The temperature peaked at 102 °F on August 2. Colonial Downs, a horse track in New Kent County, Virginia, canceled horse racing because of the 100 °F heat. The Saratoga Race Course, north of Albany, canceled racing at the horse track for the first time in its history on August 2.
By August 8, the heat wave had passed for most areas, but persisted in the South and Southeast, with continued reports of mortality in Oklahoma.
Read more about this topic: 2006 North American Heat Wave