September 2025 Overview – Midwestern Regional Climate Center

Preliminary Temperature

The preliminary average September temperature for the Midwest was 66.2°F, which was 2.6°F above the 1991-2020 normal. The entire region had anomalous warmth, ranging from about 1°F above normal in the southeast to 5°F above normal in the northwest (Figure 1). Preliminary statewide average temperatures ranged from 1.5°F above normal in Kentucky to 3.9°F above normal in Minnesota. Preliminary rankings indicate that Minnesota had its 7th warmest September on record. The Midwest was notably cool to start the month. Des Moines, Iowa, and Minnesota’s Twin Cities had the 5th coldest start to September with records dating back to the 1870s. Temperatures began to warm from west to east across the region during the second week of the month, with warmth reaching into the 90s in Iowa and Missouri. Carrollton, Missouri, experienced seven consecutive days of maximum temperatures above 90°F from September 12 to 18, marking the third-longest September stretch since 1893. By mid-month, above-normal warmth blanketed the entire region, with locations across the northwest experiencing average temperatures 10 to 12°F above normal from September 15 to 21 (Figure 2). The unseasonal warmth lingered region-wide through late September.

Preliminary Precipitation

Preliminary September precipitation totaled 2.51 inches for the Midwest, which was 0.91 inches below normal, or 73 percent of normal. The central Midwest had widespread precipitation deficits of 10-50 percent of normal (Figure 3). Precipitation across the far southern Midwest was near to slightly above normal, with an isolated area along the Kentucky-Ohio border having 150-175 percent of normal precipitation for September. Preliminary statewide precipitation totals ranged from 0.63 inches above normal in Kentucky to 1.94 inches below normal in Illinois. Preliminary rankings indicate that Illinois had its 11th driest September on record. Notably, a large swath of the region straddling the Mississippi River from Dubuque, Iowa, to south of St. Louis, Missouri, had about two consecutive weeks with no measurable precipitation in early- to mid-September. The far eastern region, from southern Michigan to western Kentucky, had a similar 2-3-week dry stretch. In central Illinois, Peoria had its 3rd driest September in 140 years with just 0.09 inches for the month, which was 3.39 inches below normal. Bloomington, Illinois, also had its 3rd driest September with 0.38 inches. Moline, Illinois, with 152 years of data, had its 6th driest September on record with just 0.71 inches measured. Across the region, other long-running observation sites had a top 5 driest September, including Cleveland (Ohio), Jackson (southern Michigan), Port Huron (eastern Michigan), and Alpena (northern Michigan) (Figure 4).

Drought

Drought conditions expanded and intensified across the Midwest during September. The month closed with about 66 percent of the region classified as abnormally dry or in drought according to the U.S. Drought Monitor (USDM) (Figure 5). For comparison, the month began with 47 percent of the Midwest experiencing drought or abnormally dry conditions (Figure 6). Dryness and drought were widespread across the lower Midwest and Michigan, including about 10 percent of the area in severe drought (D2). A multi-county area in northwest Ohio and northeast Indiana closed the month in extreme drought (D3). Several pockets across the lower Midwest and Michigan had two classes of degradation on the USDM over just four weeks during September. As conditions rapidly declined, pasture and range conditions deteriorated, water levels in stock ponds became low, and many locations implemented burn bans due to heightened fire risk.