Last month was the hottest September in Missouri since the National Weather Service began collecting data in 1890.
That applies to Columbia, which had 16 days that registered 90 degrees or above in September and an average high temperature of 87.2 degrees.
Statewide, the average temperature was 77 degrees, which breaks the previous September record of 74.8 degrees set in 1931.
Southwest Missouri was hotter and drier than other parts of the state, with recorded temperatures 10 to 12 degrees above average, said Brad Charboneau, a meteorologist with the National Weather Service in St. Louis.
Columbia’s average temperature in September was also 77 degrees, surpassing the average of 75.8 degrees recorded in both 1897 and 2019, according to the National Weather Service.
The average high temperature in Columbia last month was 87.2 degrees, more than 7 degrees higher than the typical average high of 80.1 degrees. It was also higher than last year’s average of 84 degrees.
The 16 days when temperatures reached at least 90 degrees in Columbia this year surpassed the seven days with 90-degree temperatures in 2025. Normally, there are only three days in September that hit at least 90 degrees.
Also in September, 13 days never dipped below 70 degrees, tying the record set in 1895 in Columbia. Additionally, four days in September tied or set records for the warmest overnight low temperatures in Columbia.
September was also unusually dry, with only 1.57 inches of rain during the entire month. The normal amount is 3.83 inches, according to the National Weather Service.
Similar conditions are forecast for the rest of October, Charboneau said. The last half of the month is not likely to be as hot as the first half has been, but above-average temperatures are likely.
Jet stream patterns and southwesterly winds have contributed significantly to the high temperatures in Missouri, he said.
“If you have that pattern day after day, it just compounds on itself, and you end up with these extended stretches of really warm temperatures,” he said. “We just have not been able to break out of that pattern.”
The lack of precipitation has also contributed to daily temperature swings, he said. Drier air allows temperatures to cool more at night and warm more during the day, resulting in a wider range of highs and lows. These swings are more prominent in the fall because of lower humidity.
The increased frequency of cold fronts during the fall transition season also adds to inconsistent daily temperatures, Charboneau said. These fronts can cause double-digit temperature changes from one day to the next.
“We have this kind of clash between like air masses,” he said. “The colder air is starting to come down from Canada and pushing out the warmer summer air, so that’s why, in the spring and in the fall in particular, we have these bigger day-to-day swings.”
