Autumn returned to Oklahoma nearly right on cue during the last week of September thanks to a moisture-laden cold front. The temperatures got downright chilly with lows in the 40s and 50s and highs in the 60s and 70s for a couple of days, although temperatures zoomed back into the 80s on the month's final day. The cold front provided a brief respite to what had become, at least for most of the state, a decidedly dry and warm September. The late heroics by Mother Nature were not enough to avoid the inevitable, however, as the month finished both drier and warmer than normal. According to preliminary data from the Oklahoma Mesonet, the statewide average temperature was 75.4 degrees, 3 degrees above normal and the 22nd warmest September since records began in 1895. The month's highest temperature, 108 degrees, occurred at Waurika on the first day of the month. Kenton was the winner of the lowest temperature contest with a reading of 39 degrees on the 28th. The last triple-digit temperatures of September, and almost certainly for the year, occurred at several locations on the eighth.
The rainfall was a bit trickier since the totals were quite variable across the state. Nevertheless, the statewide average total was 2.60 inches, 1.21 inches below normal and the 51st driest September on record. Kenton, normally one of the driest stations in the state, nearly led all Mesonet sites with a whopping 6.2 inches of rainfall, but was eventually bested by Burbank's 6.5 inches. Those two generous totals stand in stark contrast to the fortunes of most of southern Oklahoma. The Mesonet site at Tishomingo had a September total of 0.74 inches, and Hollis in the far southwest came in with the state's lowest total of 0.55 inches. The Panhandle region was the big winner with their 13th wettest September on record at more than an inch above normal. South central Oklahoma had an average total of 1.71 inches, 2.63 inches below normal to rank as the 27th driest for that area. Oklahoma City, which had been on pace to break their annual rainfall total, finally came back to earth with a total of 1.95 inches. That falls well below their normal September total of 4.06 inches. Their January-September total of 47.13 inches is still the second highest total on record for that period, trailing 2007's 49.27 inches. Oklahoma City's normal annual precipitation total is 36.52 inches. Tulsa has experienced differing fortunes during 2013, unfortunately. Their September total of 1.25 inches was 2.04 inches below normal and brought their January-September total to 25.88 inches, their 35th driest such period on record and nearly 6 inches below normal. Tulsa's normal annual total is 40.93 inches. Records for Oklahoma City and Tulsa date back to 1891 and 1894, respectively.
The widespread rains late in the month helped improve drought conditions that had been creeping throughout the state since mid-August. The U.S. Drought Monitor had gone from 38 percent of the state in drought at the end of August to 49 percent on the final September map. The southwest continued to be the hardest hit area with Jackson and Tillman counties covered by the "exceptional" drought, the worst category on the Drought Monitor intensity scale. The late-month moisture will be reflected on the first October Drought Monitor map.
The October outlooks from the National Weather Service's Climate Prediction Center (CPC) call for increased chances of above normal temperatures for the entire state, and below normal precipitation across northwestern Oklahoma. Accordingly, that led CPC to issue a drought outlook for October that sees drought persisting across those areas where it currently exists, but no intensification across the rest of the state.
Link to the October temperature and precipitation outlooks from the Climate Prediction Center:
Link to the October U.S. Drought Outlook:
Link to the latest U.S. Drought Monitor report (Oklahoma):