May 2024 Overview – Midwestern Regional Climate Center

Temperature

The average May temperature for the Midwest was 62.7°F, which was 3.0°F above the 1991-2020 normal. Temperatures were slightly above normal in the northwest portion of the region, increasing up to 6.0°F above normal across the Ohio River Valley (Figure 1). Statewide average temperatures ranged from 1.6°F above normal in Minnesota to 4.6 °F above normal in Ohio (Figure 2). Final rankings indicate Ohio tied for the 9th warmest May since 1895. Muskegon, Michigan, had its 4th warmest May in 128 years, with an average temperature of 62.5°F. Over a dozen long-running stations across the southeastern Midwest, including locations in southern Illinois, Indiana, Ohio, and Michigan, had a top ten warmest May (Figure 3). The average spring (March-May) temperature for the Midwest was 3.4°F above normal, with each of the three months in this period running 2.3-4.4°F above normal (Figure 4). Final rankings indicate that spring 2024 was tied for the 4th warmest on record.

Precipitation

May precipitation totaled 5.36 inches for the Midwest, which was 0.98 inches above normal, or 122 percent of normal (Figure 2). Final rankings indicate the Midwest had its 10th wettest spring since 1895. May precipitation totals were 2-8 inches above normal in the region's northwest and far southern portions (Figure 5), which is over 200 percent of normal for many locations (Figure 6). Precipitation was within 2 inches above or below normal across the central Midwest. May statewide precipitation totals ranged from near normal in Illinois to just under 2.6 inches above normal in Iowa and Kentucky (Figure 2). Final rankings indicate that Kentucky had their 6th wettest and Iowa had their 7th wettest May on record. Minnesota had their 9th wettest May on record. Scottsville, Kentucky, had its 2nd wettest May in 78 years, with 12.61 inches of rainfall. Numerous stations across the northern half of Iowa had a wettest or 2nd wettest May, with rainfall totaling 8-11 inches (Figure 7). Spring (March-May) precipitation for the Midwest totaled 12.51 inches, which was 1.89 inches above normal (Figure 4).

Drought

Ample precipitation across the region supported continued drought improvement throughout May. Less than 1 percent of the region was in drought by month’s end, and just 7 percent had abnormally dry conditions (Figure 8) June 2020 that the state was completely drought-free.

Severe Weather

While May is typically a stormy month across the Midwest, this year was unusually active (Figure 9). Regionwide, there were 219 preliminary tornado reports, which is about 4.5 times the median number of reports from 2000-2021 and the greatest number of preliminary May tornado reports since 2000. There were 1,188 preliminary wind reports and 482 preliminary hail reports, both above May's long-term median count.

There were several notable events during the month. Over 30 confirmed tornadoes touched down from Iowa and Missouri eastward through Ohio on May 6-7, with hundreds of hail and wind reports, including reports of 4-inch diameter hail in Michigan. On May 21, an EF-4 tornado cut a 44-mile path across southeast Iowa, resulting in 5 fatalities, while a broader swath of severe storms affected Iowa, Minnesota, Illinois, and Wisconsin. A long-lived complex of intense winds (derecho) and about 20 confirmed tornadoes traversed Iowa and Illinois on May 24. A large severe weather outbreak across the lower Midwest brought over 750 preliminary severe weather reports on May 26 and fatalities in Missouri and Kentucky.