December 1-7, 2023

Abnormal December Warmth Grips The Region

Temperatures were above normal across the board. This was especially the case over the western Midwest. In northern and western Minnesota, the average temperature for the week was 10-15°F above normal. The rest of the region was generally in the 3-6°F range (Figure 1).

Minimum temperatures were quite a bit above normal across most of the region, averaging 4-8°F above normal across almost every state (Figure 2). At the beginning of the period, minimum temperatures were above normal in Ohio, Indiana, Illinois and southeast Michigan. Chicago had its third warmest minimum temperature in December, with an observation of 39°F. Youngstown, Ohio and Toledo, Ohio both had the fourth warmest minimum temperatures at 43°F, which was 14°F and 13°F above normal, respectively. This continued across much of the region on December 2. Lexington, KY had its 2nd warmest minimum temperature at 53°F.

By Monday, December 4, temperatures were cooler, but not in northern Minnesota, where International Falls and Hibbing both had their warmest minimum temperature on record, at 29°F and 31°F respectively. On December 7, Kirksville, Missouri had a low of 40°F, which was 16°F above normal and the warmest on record. On the same day, Quincy, IL had its fourth warmest minimum temperature at 40°F.

Maximum temperatures were generally 2-4°F above normal region-wide, save Minnesota, where much of the state was 10-15°F above normal for the period (Figure 3). The warmth during the first week of December was quite anomalous. A warm front was lifting across Minnesota on December 6 (Figure 4). Wheaton, MN, near the border with SD, had a maximum temperature of 53°F on December 6. This was 24°F above normal, and the warmest on record in 90 years of recordkeeping. By December 7, even more locations were breaking records. There were over 50 high temperature records during the week, mostly west of the Mississippi River (Figure 5). A maximum temperature of 46°F on December 7 was tied for the warmest on record for International Falls, Minnesota. The same temperature was the warmest on record for Hibbing, Minnesota. That was 22°F above normal for both locations. Red Lake Falls had their warmest December 7 in over 100 years of recordkeeping, with a temperature of 53°F, a whopping 29°F above normal. Further south, Mason City, Iowa recorded a temperature of 55°F, 22°F above normal and the warmest on record. In St. Joseph, Missouri, a temperature of 67°F was 21°F above normal and the warmest on record.

Rain To the South, Snow to the North

Precipitation varied across the region this past week. Parts of Illinois, Missouri and points eastward received 0.5-1 inch of precipitation, with isolated spots receiving more (Figure 6). Most of this precipitation fell early in the period, with a system that came through and largely brought rain. Decatur, Illinois received 1.07 inches on December 1, which tied the previous daily record. Battle Creek, Michigan received 0.68 inches on December 1, which was also a daily record.

It is important to note that most of Minnesota and Iowa, where rain is seriously needed, saw little to no precipitation. Des Moines, Iowa recorded no measurable precipitation during the week, with only trace amounts December 3-5. Sioux City, Iowa only recorded a trace amount of precipitation on December 2, and none any other day during the period.

One place that measured appreciable snowfall was the Great Lakes, and more specifically, Michigan. Parts of the state received 3-6 inches on the back end of a low pressure system early in the week (Figure 7). Isolated spots in Wisconsin also received around 3 inches from this same system.

Drought Persists

A lack of appreciable rain in November and into the first days of December prevented any improvements across the Midwest. In fact, minor categorical adjustments were made across the region, and all of them in the wrong direction. Abnormally dry conditions (D0) now cover just over 75 percent of the Midwest (Figure 8). Even extreme drought (D3) expanded ever so slightly. That extreme drought still included most of eastern Iowa at the end of the period. Slight expansions of moderate drought (D1) were made in Illinois, Missouri, and along the Mississippi River in Minnesota.