September sees summer comeback

By GARY McMANUS

Oklahoma Mesonet

The early taste of fall that delighted many Oklahomans at the end of August lingered through the first week of September before summer grabbed the remote control again. Gone were the autumn-like highs in the 60s and 70s, replaced by the more customary 80s and 90s. Despite that return to normalcy, Mother Nature couldn’t resist one more twist: for the first time since 2008, the Oklahoma Mesonet failed to record a single 100-degree temperature during September. The last triple-digit highs—likely the year’s final—came back on Aug. 28 at several sites in southwest Oklahoma.

The impressive rains of August failed to carry far into September, leaving deficits of 2–4 inches common across much of Oklahoma.

Read more: September sees summer comeback

Far western Oklahoma and the Panhandle managed surplus amounts, continuing a trend from the previous month. Statewide, the month finished 1.41 inches below normal with an average of 1.91 inches, the 27th-driest September since records began in 1895.

Central Oklahoma fared the worst, with an average deficit of 2.87 inches—its eighth-driest September on record. In contrast, the Panhandle and northwest Oklahoma enjoyed a surplus of 0.71 inches, ranking as their 42nd-wettest.

The Sallisaw Mesonet site led the state with 4.94 inches, while Marena recorded only 0.11 inches. Just 21 of the 120 Mesonet sites topped 3 inches, and only three reached at least 4 inches.

Despite September’s shortfalls, rainfall for 2025 remains impressive. Much of the state is still running surpluses of 6–12 inches, thanks to the abundant rains of spring and summer, including April’s record-setting statewide average of 8.74 inches. Through the first nine months of the year, the statewide average stood at 34.15 inches—5.58 inches above normal—ranking as the 11th-wettest January–September on record for Oklahoma. The Sallisaw Mesonet site led all totals with 53.5 inches, 16.8 inches above normal. Even Kenton, typically among the driest locations, recorded 14.7 inches—nearly an inch above its normal.

Long-term moisture surpluses have so far prevented widespread drought expansion during September’s dry spell, but warning signs are emerging if beneficial rains do not return soon. By the end of the month, drought coverage on the U.S. Drought Monitor remained low at 3% of the state, while another 24% was classified as “abnormally dry,” a precursor to drought on the Monitor’s scale. Although still limited, the 3% drought coverage was the highest since May 27 of this year.

 

· Statewide average temperature: 73.8°F, 0.9°F above normal—the 56th-warmest September since records began in 1895

· Temperature extremes: High of 99°F at Grandfield on Sept. 11 and 12; low of 45°F at Boise City on Sept. 25 and at Eva on Sept. 26; highest heat index, 109°F at Madill on Sept. 23; lowest wind chill, 41°F at Boise City on Sept. 25

· Warmest and coolest locations: Highest monthly average, 78°F at Grandfield; lowest, 67.9°F at Kenton

· Statewide average precipitation: 1.91 inches, 1.41 inches below normal—the 27th-driest September on record

· Rainfall extremes: High of 4.94 inches at Sallisaw; low of 0.11 inches at Marena

· Rainfall totals below 2 inches: 70 instances recorded at the 120 Oklahoma Mesonet sites

The Climate Prediction Center’s October outlook indicates increased odds of above-normal temperatures and below-normal precipitation across the state. Those odds for below-normal precipitation are slightly lower across the northwestern quarter of Oklahoma. The CPC’s October drought outlook calls drought development “likely” across much of the southeastern two-thirds of the state by the end of the month.

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