August 15-21, 2024

Temperatures

Average temperatures ranged from slightly above normal in the far northwest and southwest, to slightly below normal across the Ohio Valley (Figure 1). At most, average temperatures were generally 1-3°F below normal in the east, and 1-3°F above normal in northwestern Minnesota and southwestern Missouri. In Frankfort, Indiana, the average temperature on August 21 was only 58°F, the lowest average temperature for a single day in August since 2009.

Minimum temperatures averaged below normal across the east by 1-3°F, and above normal across the west by as much as 6°F, mainly in Minnesota (Figure 2). Through the middle of the region, from Michigan into Wisconsin, Illinois and Iowa, minimum temperatures were near normal. A station in Washington, Indiana with over 120 years of records observed a minimum temperature of 50°F on August 21, which was the coldest August temperature in 11 years.

Meanwhile, maximum temperatures averaged below normal by generally 2-4°F for the whole region (Figure 3). Dennison Water Works, a station with 82 years of records, observed maximum temperatures of 70°F or less two consecutive days—August 20-21—for the first time in August since 2015 and 9th time since records began.

Precipitation/Drought

Precipitation was scattered across the region this week. Southern Missouri, central Illinois, eastern Kentucky, Michigan’s Upper Peninsula (UP) and northern Michigan all received near or more than 200 percent of normal precipitation (Figure 4). Meanwhile, the St. Louis area, southern Illinois, southwestern Indiana, western Kentucky and southeastern Ohio all received 50 percent or less of normal precipitation.

The scattered nature of rain did not help drought conditions. As of August 19, Ohio had its highest extent of extreme drought (D3) since the Drought monitor began in 2000 (Figure 5). Elsewhere in the region, mainly abnormally dry (D0) conditions were noted.

Severe Weather

There were 175 storm reports this week, and 150 were solely wind reports (Figure 6). Most of these occurred in Illinois, Kentucky, Missouri, and Ohio. On August 17, Kentucky Mesonet station in Winchester, Kentucky measured a straight-line wind gust of 82 mph.