Regional Variation in Temperatures

Average temperatures varied up to 8°F above normal in the northwest to as much as 6°F below normal in the southeast (Figure 1). Much of Michigan, Missouri, southern Wisconsin, eastern Iowa, and northern Illinois faired close to normal temperatures. Minnesota had the largest temperature departure (+6.4°F), followed by Wisconsin (+3.0°F), Iowa (+2.3°F), Michigan (0.9°F), Missouri (0.3°F), Illinois (-1.1°F), Indiana (-1.4°F), Ohio (-2.3°F), and Kentucky (-2.6°F). Maximum temperatures were above or at normal throughout the region, excluding portions of Ohio and Kentucky, where the largest departures were near 8°F below normal. Maximum temperatures in northwest Minnesota were near 8°F above normal for the week (Figure 2). Minnesota, Iowa, Wisconsin, and the Upper Peninsula of Michigan saw above normal minimum temperatures, with departures in excess of 9°F occurring in northern Minnesota. As for the rest of the Midwestern states, most saw below normal minimum temperatures, with the departures up to 7°F occurring in Illinois, Indiana, and Kentucky (Figure 3). Additional locations in the Midwest saw their first 32°F temperature this week (Figure 4).

Widespread Below-Normal Precipitation

The pattern of dry weather continued for the first week of October as most of the region saw below-average precipitation (Figure 5) with maximum totals of less than 0.5 inches (Figure 6). Eastern Kentucky and Ohio experienced higher precipitation (up to an inch) as a result of the remnants of Hurricane Ian. All states received less than 30% of normal precipitation, and multiple stations in each state reported that this week was one of the driest starts to October on record (Figure 7). The dry weather affected water resources across the Midwest as several more locations reported below-average streamflows, especially in Michigan, Indiana, Illinois, Iowa, and Missouri (Figure 8). Reports indicated that portions of the Mississippi River are low enough that the movement of goods may be impacted.

Drought Monitor Update

After minimal precipitation throughout the Midwest this week, the October 4 US Drought Monitor indicated a 16.95% increase of land abnormally dry or in drought compared to last week (Figure 9). Portions of southwestern Missouri remained in an Exceptional Drought (D4), and the amount of land in an Extreme Drought (D3) and D4 more than doubled since last week. D3 was added in southern Minnesota and expanded in Missouri. Areas of Severe Drought (D2) were expanded in southern Minnesota, parts of Iowa, and central Missouri. Areas of Moderate Drought (D1) were expanded in central Minnesota, northern Wisconsin, Iowa, southern Illinois, and eastern Michigan. Abnormally Dry areas (D0) were added and expanded all across the region this week.