Drought surged across Oklahoma as the driest September since 1956 took its toll on the state’s landscape. The amount of drought in the state remained largely unchanged through September at approximately 99%, but the intensity of that drought increased dramatically according to the U.S. Drought Monitor. Extreme and exceptional drought, the Drought Monitor’s two worst categories, jumped from 47% on Aug. 30 to 64% at the end of September, the highest such levels seen in the state since Feb. 19, 2013. Exceptional drought alone rose to 17%, its highest level since May 8, 2018. Soil moisture plummeted and fire danger increased in the hot, dusty conditions. The USDA estimated that 91% of the state’s topsoil moisture was considered “short to very short” by the end of the month. The Oklahoma Mesonet measured critically dry soils down to at least 32 inches, which helped boost large wildfire potential into the extreme category. Farm ponds were reported low to completely dry across many parts of the state, and the bulk of Oklahoma’s larger reservoirs sat 5-10 feet below normal through the third week of September.
The statewide average rainfall total was 0.71 inches according to the Oklahoma Mesonet, 2.61 inches below normal and ranked as the fifth driest September since records began in 1895. None of the 120 Mesonet sites came even close to a surplus for the month. Fittstown led the way with 2.36 inches. Three western Oklahoma sites—Eva, Grandfield, and Hollis—shared the bottom spot with three-hundredths. Eighty-seven sites recorded less than an inch for the month, and 54 of those sites actually had less than a half-inch. Much of the state had gone at least a month without a quarter-inch of rainfall in a single day, with some locations across northern Oklahoma missing out for more than 60 days. The first nine months of the year remained squarely on the dry side with a statewide average of 22.01 inches, 6.56 inches below normal and ranked as the 21st driest January through September on record. The Oklahoma Panhandle was particularly dry at 11.63 for their ninth driest such period on record.
The statewide average temperature of 75.7 degrees ranked as the 24th warmest September since records began in 1895, 2.8 degrees above normal. Temperatures were solidly above normal for most of the month, at times 10 to 15 degrees higher than the seasonal averages. The 120 Mesonet sites recorded triple-digit temperatures 342 times on 10 separate days, with 102 degrees being the top mark at many locations across several days. The month’s—and possibly the seasons’—final 100s occurred on the 25th at the Burneyville, Hugo, and Valliant Mesonet sites. September’s coldest reading of 36 degrees occurred on the 30th at Wister. That reading and the 39 degrees at Talihina the same day were the first 30s recorded in the state since May 22. The year continued very warm with a January through September statewide average of 64.8 degrees, a degree above normal and ranked as the 22nd warmest such period on record.
The Climate Prediction Center’s outlooks for October portray possible warm and dry conditions continuing, with increased odds of above normal temperatures for the entire state and below normal precipitation for all but the western Panhandle. The western Panhandle has equal chances for above-, below-, and near-normal precipitation for October. CPC’s October drought outlook indicates drought persisting across the entire state through the end of the month, and expanding to cover most of the Southern Plains through that same period.