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July 2023

  • Monthly Summary

Temperature The average July temperature for the Midwest was 72.3°F, which was 0.5°F below the 1991-2020 normal. Temperatures were 1-3°F below normal in the northwest and near to slightly above normal across the central and southeastern portions of the region (Figure 1). Statewide average temperatures ranged from 1.6°F below normal in Minnesota to 0.3°F above normal in Ohio. High heat and humidity settled across the Midwest during the last week of July, with maximum heat index values exceeding 110°F as far north as Minnesota and Wisconsin. Throughout the month, there were 289 daily high temperature records broken or tied (Figure 2), with nearly all records achieved during the last week of July (Figure 3). There were 312 daily low temperature records in July, with most records having been set in the western and southern portions of the region mid-month (Figure 4).

Precipitation July precipitation totaled 4.03 inches for the Midwest, which was 0.07 inches below normal, or 98 percent of normal. Precipitation was near to above normal east of the Mississippi River and below normal to the west, with mixed conditions in Missouri (Figure 5). Statewide precipitation totals ranged from 2.12 inches below normal in Minnesota to 1.49 inches above normal in Michigan. Final rankings indicate Michigan had the 6th wettest July on record. Chicago’s Midway Airport had the wettest July on record, dating back 93 years, with 11.28 inches of precipitation for the month. Port Huron, Michigan had the wettest July on record with 7.14 inches. Paducah, Kentucky had the 2nd wettest July on record with 10.6 inches of precipitation for the month. There were 373 daily high precipitation records broken or tied in July, with records set across the entire region (Figure 6).

Drought About 83 percent of the Midwest was abnormally dry or in drought in late July (Figure 7). Drought conditions improved throughout the month along and east of a line from southeast Missouri to Michigan. Heavy rainfall resulted in a rare 2-category improvement on the US Drought Monitor map from July 11 to July 18 across northern Illinois, southern Michigan, western Indiana, and eastern Missouri (Figure 8). Drought persisted or intensified across Minnesota, Wisconsin, and northern Missouri. By month’s end, 71 percent of pasture and rangeland (Figure 9) and 44 percent of corn crops were rated poor to very poor in Missouri (Figure 10). Topsoil moisture was short to very short on 61-76 percent of cropland west of the Mississippi River (Figure 11).

Air Quality
Ongoing Canadian wildfires continued to periodically affect the Midwest throughout July. The Air Quality Index exceeded 150 (i.e. unhealthy levels) for millions across Iowa, Illinois, Indiana, Kentucky, and Ohio on July 16th (Figure 12,, and 17th (Figure 13, Conditions again reached unhealthy levels across the region on July 25 (Figure 14,

Illinois Severe Weather Multiple rounds of severe weather resulted in an unusually high number of heavy rain events, damaging wind events, and tornadoes in Illinois (Figure 15). The Storm Prediction Center recorded 23 preliminary tornado reports, which is the highest count dating back to 2000 and well above the 2000-2021 median of 3 for July. Flash flooding affected the Chicago area on July 2 when a slow-moving storm system dropped 3-8 inches of rain. City officials had to reverse the flow of the Chicago River to reduce coastal flooding on Lake Michigan. Other notable events occurred on July 12, 14, 19, 27, and 28.

Flash Flooding July 18-19 Extreme one-day rainfall totals were measured across a broad swath of southeast Missouri, southern Illinois, and western Kentucky on July 18th and 19th, triggering flash flooding, water rescues, and infrastructure damage (Figure 16). Rainfall totals ranged from 5-10 inches, with most falling in less than 12 hours. Mayfield, Kentucky measured 8.13 inches at the COOP weather station on July 19, while a nearby Kentucky Mesonet station in Graves County recorded a 24-hour total of 11.28 inches. This rainfall total exceeded the current statewide 24-hour precipitation record of 10.48 inches set in 1997, but a formal investigation would be required before a new record could be named.

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