October 2023 Overview – Midwestern Regional Climate Center

Temperature

The average October temperature for the Midwest was 53.7°F, which was 2.3°F above the 1991-2020 normal. Temperatures ranged from about 1-4°F above normal across the entire region with no specific spatial pattern to the warmth (Figure 1). Statewide average temperatures ranged from 1.6°F above normal in Kentucky to 2.6°F above normal in Wisconsin and Minnesota. The month was characterized by dramatic temperature swings from week to week, as is typical for this time of year. October started with record and near-record warmth, especially across the upper Midwest. High temperatures averaged 15-25°F above normal from October 1-4 for most of Minnesota, Wisconsin, and Iowa (Figure 2). Excessive warmth even prompted the cancelation of the Twin Cities Marathon on October 1. Temperatures oscillated below and above normal through mid-month before ending the month with record and near-record cold across the lower Midwest. A strong cold front traversed the region October 27-29, causing daily high temperatures to drop by about 30°F. Numerous locations, particularly across the lower Midwest, had a top five coldest Halloween (October 31) on record, with high temperatures 15-20°F below normal (Figure 3). Despite the late-month cold snap, a handful of long-running stations in central and northern Michigan and northeast Ohio had monthly minimum temperatures among the top 10 warmest on record.

Precipitation

October precipitation totaled 3.23 inches for the Midwest, which was 0.13 inches above normal, or 105 percent of normal. Moisture was quite variable across the region. Precipitation totaled 125-300 percent of normal along an axis stretching from the Iowa-Minnesota border eastward to northwest Ohio (Figure 4). Conversely, totals were 25-75 percent of normal for much of the lower Midwest. Statewide precipitation totals ranged from 1.07 inches below normal in Kentucky to 1.13 inches above normal in Wisconsin. Rankings indicate Wisconsin had the 13th wettest October on record. The first widespread snowfall of the season occurred on Halloween (October 31) across the upper Midwest, with totals ranging from less than 1 inch to as much as 11 inches (Figure 5).

Drought

Increased moisture helped reduce the severity and extent of dryness and drought throughout the Midwest in October. The month concluded with about 65 percent of the region affected by dryness or drought; a 21 percent improvement compared to the beginning of October (Figure 6). Portions of Minnesota, Wisconsin, and Indiana had 2-3 class improvements on the US Drought Monitor map over the month (Figure 7). Drought was the most severe in eastern Iowa and west-central Missouri. Drought remained widespread along and west of the Mississippi River and sporadic to the east. About 42 percent of the region had no dryness or drought by month’s end.