Missouri Climate Center

September 2023 Weather and Its Impacts on Missouri

Dr. Pat Guinan
Climatologist
MU Extension Associate Professor Emeritus

Seasonably cool weather dominated the first half of September followed mostly by above average temperatures during the latter half of the month, Figure 1. Accordingly, the first half of the month was slightly cooler than the latter half.

Preliminary data indicate a statewide average temperature of 70.4 °F, or 2.2 degrees above the long-term average. The mild month followed the trend over the past decade with 8 out of the past 10 Septembers warmer than average, Figure 2. Every month this year has been above average, Figure 3.

Dry conditions impacted much of Missouri in September with preliminary data indicating a statewide average of 1.98 inches, 2.12 inches below the long-term average. It was the seventh consecutive dry September for the state. Over the past 50 years, there have been 36 drier than average Septembers, or 72% of them, Figure 4. It was also the fourth month during the growing season this year with below average precipitation, Figure 5.

September rainfall totals were variable across Missouri with radar-estimates indicating highest amounts over southwestern Missouri and driest conditions in northeastern sections, Figure 6. Some of the heaviest and lightest rain gauge reports for September are listed in Table 1.

Missouri High and Low Rainfall Extremes for September 2023*

	Station Name*	County	Rainfall (in.)

Heaviest
	Anderson 6.8W	McDonald	9.76
	Galena	Stone	8.04
	Aurora 2.7S	Lawrence	7.88
	Golden City 6S	Dade	7.70
	Springfield 4.9SE	Greene	7.73
Lightest
	Kirksville 1.6N	Adair	0.18
	St. Clair 3W	Franklin	0.23
	Shelbyville 0.3SE	Shelby	0.23
	Columbia 3.4WNW	Boone	0.27
	Mexico	Audrain	0.29
*Rain gauges are from the NWS Cooperative Network and CoCoRaHS observations.
Table 1.

The U.S. Drought Monitor for September 26, 2023, showed over half of Missouri experiencing moderate drought or worse, Figure 7. Driest conditions were occurring over west central Missouri where most of the region was experiencing severe to extreme drought. Pockets of severe to extreme drought were occurring in central and northeastern sections.

Dryness impacts continued to accumulate across the state during September. Parts of west central, central, and northeastern Missouri have been especially hard hit, where severe to extreme drought has persisted for much of the growing season. There have been reports of significant crop and pasture losses, and dwindling feed and water supplies for livestock. Dry September conditions provided little or no opportunity for renewed grass growth for pastures and lawns statewide and seeding efforts for cool season turfgrasses were severely hampered.

According to the Missouri Agricultural Statistics Service, as of October 1, 2023, most of the corn was in fair to good condition at 30% and 32%, respectively. Remaining corn conditions this year were 3% excellent, 19% poor and 16% very poor. Corn harvest was running slightly ahead of schedule at 42%, compared to the 5-year average of 40%. Most of the soybean crop this year was reported in fair (33%) to good (43%) condition with only 5% reported as excellent. Remaining soybean conditions were 14% poor and 5% very poor. Last year, at this time, soybean was 7% very poor, 11% poor, 33% fair, 44% good and 5% excellent.

Hay and roughages were 38% adequate with 0% surplus this year and 36% short and 26% very short. Stock water supplies were mostly adequate at 61%, with 30% short and 9% very short. Pastures were reported 0% excellent, 20% good, 38% fair, 33% poor, and 9% very poor condition.

Topsoil moisture conditions were short (37%) to adequate (37%), while 0% were surplus and 26% very short. The subsoil moisture conditions were reported 0% surplus, 34% adequate, 41% short, and 25% very short.

Most sections of the Missouri will experience their first fall frost during October, Figure 8. Using climatology, the northern quarter of Missouri and eastern Ozarks will generally experience a light freeze (32°F or cooler) by mid-October. Central Missouri and the western Ozarks will experience a light freeze by October 21st, and a few days later in urban areas. The Bootheel will have a light freeze typically toward the end of October or early November. For more information on frost/freeze probabilities for Missouri, including additional temperature thresholds, please visit the following link: http://ipm.missouri.edu/FrostFreezeGuide.

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