July Heat Becomes Historic

Fueled by exceptional drought and a seemingly impenetrable heat-dome, July roared through Oklahoma’s legendary heat waves of the past to become the state’s hottest calendar month on record. According to data from the Oklahoma Mesonet, the July statewide average temperature finished 7.5 degrees above normal at 89.1 degrees, smashing the previous record of 88.1 degrees set back in July 1954. Statewide averages date back to 1895. The news was equally grim on the rainfall side of the ledger. The statewide average rainfall total was 0.70 inches, more than 2 inches below normal and the fourth driest July on record. Combined, the 2011 June-July period was the hottest and driest on record statewide, an ominous achievement with another month of summer yet to go. Through seven months, 2011 ranked as the eighth warmest and second driest on record.

Oklahoma City’s average temperature of 89.2 degrees topped the previous record of 88.7 degrees from August 1936 to become its warmest month since those records began in 1890. Oklahoma City experienced 27 days in July with a high temperature of at least 100 degrees, once again the most for any month in its history. Oklahoma City’s average high temperature of 102.5 degrees beat July 1980’s previous mark of 102.4 degrees to set another milestone. Similar records were matched at many locations throughout drought-ravaged western Oklahoma. Grandfield was the warmest spot in the state with an average July temperature of 93 degrees and an average high of 107 degrees. Grandfield continued to lead the state with 68 days at or above 100 degrees in 2011. The record stands at 86 days, set by Hollis in 1956. That site and three others have seen triple-digit highs for 40 consecutive days through July 31. Kenton’s July average of 81.6 degrees marked it as the coolest spot in the state. The highest temperature of the month, 114 degrees, was recorded at Alva and Freedom on July 9.

Of the 120 Oklahoma Mesonet stations, 93 recorded less than an inch of rainfall for the month. Walters and Burneyville recorded no precipitation for the entire month. Newkirk and Kenton led the way with 5.58 inches and 3.66 inches, respectively. Only five stations recorded more than 2 inches of rainfall. Southwestern Oklahoma received less than a quarter-inch of rainfall, on average. An average of 16.41 inches of precipitation has fallen across the state since October 1, 2010, nearly 14 inches below normal and the driest such period on record. Boise City received a scant 3.8 inches of rainfall over that time while Grandfield measured 5.6 inches. The latest U.S. Drought Monitor map released on July 28 indicates more than half of Oklahoma is experiencing exceptional drought, the worst designation possible.

Unfortunately, there is little relief in sight as the heat and drought continue to feed off one another. The latest outlooks for August from the National Weather Service’s Climate Prediction Center indicate increased chances of above normal temperatures and below normal precipitation. Their seasonal drought outlook calls for the persistence or intensification of drought conditions across Oklahoma and Texas through October.

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