October 8-14, 2023

Cooler Temps for the Midwest

After a very mild start to October, the second week was anything but that. No state in the Midwest saw above-normal temperatures. In fact, most states saw average temperatures that were 2-5°F below normal (Figure 1). Michigan’s average temperature of 46.4°F was 2.6°F below normal, and Wisconsin’s average temperature of 45.6°F was 2.8°F below normal. Ohio’s average temperature of 52.6°F was 1.4°F below normal, while Indiana’s average temperature of 53.7°F was 1.5°F below normal. Missouri was least affected by this second week cooldown, with an average temperature of 57.8°F, which hovered right near the normal of 58°F.

Minimum temperatures were also below normal, as most states saw areas with average minimum temperatures that were 2-3°F below normal (Figure 2). The Ohio Valley observed more significant temperature departures compared to other parts of the Midwest. In Cincinnati, minimum temperatures were generally 10-12°F below normal October 8 through October 11. Normal minimum temperatures between October 8 and October 14 are 45-50°F for southwestern Ohio, but they generally hovered between 35°F and 40°F, which would be more typical of parts of Minnesota and Wisconsin that time of the year.

Maximum temperatures were considerably below normal. Every state saw an average maximum temperature that was below normal, save Missouri, where a small portion of the state saw above-normal temperatures (Figure 3). In Michigan, the maximum temperature averaged 8-12°F below normal for the week. On October 8, most locations across the state saw maximum temperatures that were roughly 10°F below normal, generally ending up in the 40s to near 50°F. On October 9, many locations in northern Michigan observed temperatures up to 15°F below normal. On October 11, in Michigan’s UP, a maximum temperature of 37°F was the coldest on record for that date in Herman. Midland also had its coldest October 11, with a maximum high temperature of 48°F, which was 15°F below normal. Minnesota and Wisconsin generally saw maximum temperatures that were 5-10°F below normal for the week. A boundary began lifting north across Illinois, Indiana, and Ohio October 12-13, which created southerly flow and raised maximum temperatures into the 70s in places like Indianapolis, Indiana and Columbus, Ohio. The maximum temperature even reached 81°F in Cincinnati. However, much of the Upper Midwest remained north of the front, which yielded below-normal temperatures. The maximum temperature in Minneapolis was only 50°F on October 13, which was 10°F below normal.

Reigning in the Rain Across the Region

A low pressure system came through the Midwest October 12-14. As a result, a belt of 2 to 4 inches of rain fell through Minnesota, Wisconsin, Iowa, and Illinois (Figure 4). Elsewhere, Michigan, Ohio, and Indiana each generally observed 0.5-1.5 inches of rain. In Iowa, arguably the state with the most need for rain, isolated pockets recorded over 4 inches during just the final three days of the period (Figure 5). Camanche, Iowa observed over 4.5 inches of rain. In Cedar Rapids, an observer recorded over 3 inches of rain. Similar totals were observed in southern Minnesota, where observations in the Twin Cities were generally above 3 inches.

Despite the healthy rains for many, areas along and south of Interstate 80 only recorded, at most, 1 inch of rain. Missouri and Kentucky by far recorded the least amount of rain for the period, with most areas of each state averaging less than 0.5 inches of rain for the week.

There were minimal storm reports during the period. Most were hail reports from an event in Iowa on October 11. However, an EF1 tornado briefly touched down in Cooperstown, Illinois on October 13, causing damage to a residence and injuring one person.

Drought Persists With Notable Improvements in Spots

Drought persisted from the beginning of October into the second week of the month across the Midwest. While there were minor improvements in each drought category, they were negligible, and most areas remain unchanged. Hard-hit Iowa still had 100 percent of land dealing with abnormally dry conditions (D0), while Michigan was the least affected by drought with over 60 percent of land not meeting any drought criteria. Missouri, Minnesota, and Wisconsin continue to deal with pockets of extreme drought (D3). There was improvement in Minnesota’s Arrowhead region, where the Greater Duluth area now lives drought-free. However, for every area that exited drought classification, another area gained it. In Indiana and Ohio, moderate drought (D1) continued its expansion, with most of Indiana, half of Ohio, and northern Kentucky in D1 conditions (Figure 6).

By the end of the period, however, appreciable rainfall arrived. The system that came through the Midwest October 13-14 (Figure 7) brought 3-4 inches of rain with it. As a result, the Twin Cities was downgraded a whole drought category, with eastern and northern suburbs leaving D1 and entering D0 while the remainder of the metro, from Minneapolis south and west, went from D2 to D1. Parts of Wisconsin, including Madison, also saw substantial drought removal due to recent rain. Madison went from D1 to D0, while the area just to the south went down a whole two categories, from D2 to D0. There was also removal of D0 from Milwaukee and much of Wisconsin’s southern lakeshore. While Iowa remained largely covered by D1-D4 drought at the period’s end, it no longer had 100 percent of land in D0 or 95 percent of land in D1. Although these were the most significant drought removals in quite some time, much more rain will be necessary to end drought across the region.

Drought also continued to affect streamflow. The Wabash River at New Harmony, Indiana was down to 0.75 feet by the morning of October 14, well below the low water stage of 3.3 feet (Figure 8). However, it was in southern Illinois, southeast Missouri, and western Kentucky where the lowest river levels in the region were recorded. The Ohio River at Cairo, Illinois hit a low crest of 4.54 feet on October 8, well below the low water stage of 9.2 feet (Figure 9).