July 1-7, 2002: Intense Heat Coincides with Continuing Dryness.

The first week of July was hot as a firecracker in much of the Midwest as a high pressure ridge aloft dominated the weather pattern. The hot weather covered most of the region except for Missouri and southern Kentucky. The warmest temperatures occurred in southern Minnesota and northern Iowa, eastern and northern Wisconsin, northeastern Illinois, and northern Michigan. In these areas average daily temperatures were 6 to 8°F above normal (Figure 5). Daily maximum temperatures in the upper 80s and low 90s were common across most of the Midwest (Figure 6). The hot weather was responsible for at least 12 deaths in Chicago and four deaths in St. Louis. Some relief was felt across Wisconsin, Michigan, and the northern half of Illinois and Indiana by July 6th as a weak cold front brought slightly cooler but much less humid air to parts of the region.

Rainfall was sparse across the Midwest during the week. Widely scattered thunderstorms brought rain to parts of Missouri, Iowa, Minnesota, and western Wisconsin, but much eastern Midwest remained bone dry for the week (Figure 7). Only isolated pockets in the region received above normal precipitation amounts for the July 1-7 period (Figure 8). This is the third week of dry weather in the Midwest after six weeks of wet weather. Precipitation totals since June 15 have been well below 50% of normal for much of the Midwest, including less than 25% of normal from southeastern Iowa to central Illinois (Figure 9) is below normal across most of the Midwest except for most of Minnesota and Wisconsin. Crops were experiencing stress from the recent heat and dry weather. The heat and lack of rainfall has left the upper layers of soil very dry. In many areas where planting was delayed by the wet spring, roots have not yet developed enough to tap deeper subsoil moisture. Modeled soil moisture estimates in the upper 12 inches of soil are below the long term average across all but the northern Midwest (Figure 10).