October 15-21, 2024

Temperatures

Average temperature anomalies this week were divided by I-80, with temperature generally near or below normal to the south or above normal to the north (Figure 1). Over Minnesota and Michigan’s Upper Peninsula (UP) temperatures were as much as 10°F above normal for the week. In the Missouri Bootheel and Kentucky they were 5-6°F below normal.

Minimum temperatures average quite a bit below normal for much of the region, save the UP, northern Wisconsin and Minnesota (Figure 2). In fact, they were near 10°F below normal for the week in southern Missouri and Kentucky. In Dubuque, Iowa, a minimum temperature of 24°F was observed on October 16, the earliest such temperature in meteorological fall at that location since 2009. Danville, Illinois had four consecutive days of minimum temperatures at or below freezing from October 16-19 for the first time in October since 2000.

Maximum temperatures were 10-13°F above normal for much of the Upper Midwest (Figure 3). Along I-80, they were generally 4-7°F above normal. In fact, over 100 high temperature records were set this week, and many of them were in the Upper Midwest (Figure 4). Alpena, Michigan observed a temperature of 84°F on October 21, which was not only a daily record but the warmest temperature ever recorded this late in the calendar year. Eau, Claire, Wisconsin rose to 83°F on October 21, which was both a daily record and tied for the third latest 83°F temperature or greater in the calendar year.

Precipitation/Drought

There was largely no precipitation this week. At most, some parts of northern Minnesota, northern Wisconsin, Chicagoland, and northeast Ohio received 50 percent or less of normal precipitation (Figure 5). A variety of stations across Minnesota and Iowa had not recorded measurable precipitation in at least four weeks as of October 21. A station in Milan, Minnesota had observed no measurable precipitation for the entire month through October 21 for only the third time during October since records began in 1893. The same thing happened in Minneapolis, Minnesota, which was only the 4th time in that station’s history since 1871.

With the lack of precipitation, drought expanded for the entire region. By October 21, at least 65 percent of the Midwest was in D1 moderate drought (Figure 6). Another quarter of the region was in D2 severe drought. D3 and D4 conditions, extreme and exceptional drought, respectively, went mostly unchanged in southwest Missouri and Ohio. The largest drought expansions were made over the Upper Midwest, in similar locations to the aforementioned parts of Minnesota, northern Wisconsin, and Michigan’s UP.