May 2025 Overview – Midwestern Regional Climate Center

Temperature

The average May temperature for the Midwest was 59.1°F, which was 0.6°F below the 1991-2020 normal (Figure 1). Temperature anomalies were 1 to 6°F above normal across Minnesota, with temperatures closer to normal or slightly below normal across the region to the south and east (Figure 2). Statewide average temperatures ranged from 2.2°F above normal for Minnesota to 2.0°F below normal for Ohio. Temperature departures oscillated from above normal to near normal to below normal for the first few weeks of May before widespread below-normal temperatures blanketed the region from May 22-31. Notably, record to near-record warmth stretched across the northwest portion of the region from May 11-15 as temperatures soared more than 25°F above normal (Figure 3). Temperatures across northern Minnesota reached the mid- to upper-90s on May 11, followed by several more days with temperatures over 90°F. International Falls, Minnesota, reached 96°F on May 11, setting an all-time high temperature record for the month and becoming the highest temperature ever measured that early in the calendar year. Southern Wisconsin reached its first 90°F temperature of the year on May 15, about a month ahead of normal. Meanwhile, locations across the lower Midwest, from southern Missouri eastward along and around the Ohio River, were void of reaching 90°F during the month of May. The Midwest's average spring (March-May) temperature was 2.0°F above normal (Figure 4). Final rankings indicate that spring 2025 was tied for the 13th warmest on record for the Midwest with 2016.

Precipitation

May precipitation totaled 3.64 inches for the Midwest, which was 0.74 inches below normal, or 83 percent of normal (Figure 1). Precipitation was near to above normal across the far lower Midwest, eastern Midwest, and central Minnesota (Figure 5). Elsewhere across the central and western Midwest, precipitation was 25 to 75 percent of normal. Statewide precipitation totals ranged from 1.66 inches above normal in Kentucky to 2.25 inches below normal in Iowa (Figure 1). Several long-running stations in central and southeast Ohio had a top ten wettest May (Figure 6). Circleville, Ohio, had its 6th wettest May in 120 years, with 7.98 inches of rainfall. In western Kentucky, Mammoth Cave ended the month with 9.07 inches, becoming the 8th wettest in 85 years of recordkeeping. In southwest Missouri, the town of Nevada logged its 5th wettest May in 114 years with 11.23 inches. From northern Missouri northward to the Canadian border and northeastward into the western Great Lakes, much of the region had a 12-17 day stretch of consecutively dry weather in early May. Several long-running stations in Iowa achieved a top ten driest May. In southeast Iowa, Ottumwa measured 0.83 inches for May, the 2nd driest in 77 years of observations, and over 4 inches below normal for the month. Fayette, in northeast Iowa, had their 5th driest May in 130 years with just 1.39 inches. Final spring (March-May) precipitation for the Midwest totaled 11.34 inches, which was 0.72 inches above normal (Figure 4). Final rankings indicate that spring 2025 was the 27th wettest on record for the Midwest.

Drought

During May, the lower Midwest remained free of abnormal dryness or drought (Figure 7). Scattered areas of abnormal dryness or drought lingered across the upper Midwest with little change from the start to the end of May. The one area of notable drought expansion during May was northern Illinois and northwest Indiana, which were blanketed with moderate (D1) drought by the end of the month.

Wildfires

A prolonged stretch of warm, dry, and windy weather in early to mid-May created elevated wildfire risk across Minnesota and northern Wisconsin, with the most notable fire risk from May 11-14. In northeast Minnesota, three large fires ignited on May 12-13 and burned for weeks before full containment was achieved. Combined, these fires burned over 30,000 acres of land, destroying structures and forcing local evacuations.

May 15 Severe Weather Across the Upper Midwest

A fast-moving, potent weather system brought tornadoes, damaging winds, and large hail to the Upper Midwest and Great Lakes on May 15 (Figure 8). At least 31 tornadoes were confirmed across Minnesota, Wisconsin, and Michigan. Hail up to 3 inches in diameter fell along the southern Lake Michigan shore from Milwaukee throughout the Chicago area. Damaging winds gusting 50-80 mph were reported across a wide swath of the region, and a multi-county area in northwest Wisconsin had significant straight-line wind damage from winds that exceeded 100 mph.

May 16 Severe Weather Across the Lower Midwest and Chicago Area Dust Storm

A severe thunderstorm and deadly tornado outbreak initiated in eastern Missouri on May 16 and moved eastward across the lower Midwest, affecting Illinois, Indiana, Kentucky, and Ohio (Figure 9). At least 16 tornadoes were confirmed across the multi-state area by the National Weather Service, including an EF-4 in southern Illinois with peak winds estimated at 190 mph and a long-track EF-4 in eastern Kentucky that caused 19 fatalities. An EF-3 tornado traversed a populated area of St. Louis, Missouri, killing four people and injuring dozens more while leaving an estimated $1 billion in storm damage to the city. Two other tornadoes in this outbreak caused a combined three additional deaths, bringing the human toll to at least 26 fatalities across the region. Additionally, very large hail (tennis ball to softball size) was reported in western Kentucky and central Indiana, and a wide stretch of 60-90 mph straight-line winds ripped across central and eastern Kentucky.

As storms tracked across the lower Midwest, strong winds moved across dry farmland in northeast Illinois, kicking up a large dust storm that moved northeast into the Chicagoland area, northwest Indiana, and extreme southwest Michigan. The dust was driven by 60 mph winds, which resulted in very low visibility and crop damage. According to the National Weather Service, this area has not experienced a dust storm of this magnitude since the mid-1930s.