Monthly Overview - May 2016

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Seasonal Temperatures

May temperatures averaged within a couple degrees of normal for nearly the entire Midwest, slightly below-normal in the south and slightly above-normal in the north (Figure 1). The only exception was in northwest Minnesota where the temperatures were as much as 4°F above normal. Despite the average temperatures being near normal, daily values ranged from below-freezing into the 90s in all nine states. Spring temperatures (March to May) were warm across the region, averaging about 2°F above normal (Figure 2). This ranked the spring of 2016 as tied for the 11th warmest since 1895 for the region as a whole. Year-to-date temperatures (January to May) were also about 2°F above normal, which ranked as the 9th warmest such period in history.
 

Precipitation

May precipitation varied across the Midwest. Most of the region was slightly below-normal while southeast Missouri, Kentucky, southwest Minnesota, western Iowa, and northwest Missouri saw above-average rainfall totals in May (Figure 3). Precipitation totals were well above normal and exceeded 10 inches at several stations in Missouri and isolated stations in Illinois, Indiana, Kentucky, and Iowa. Spring precipitation totals were mostly near normal with drier areas in south central Iowa and west central Minnesota, and wetter areas along the north, south, and west edges of the region (Figure 4).
 

Drought Remained Minimal

At the beginning of May, drought coverage was only about 2% of the region (Figure 5). In the first couple of weeks of May, sufficient rains fell to lead to the elimination of drought according to the US Drought Monitor. The month ended with no drought designations in the Midwest, but there were scattered areas (less than 15%) across six states noted as abnormally dry (Figure 6).
 

Severe Weather

Severe convective weather was reported on 20 of 31 days in May, and was spread across all nine Midwest states. There was a nine-day period with no reports from the 14th to the 22nd. The 5th and the 8th also were quiet. Tornadoes were reported on ten days in May (1st, 9th-11th, 23rd-27th, and 31st), with occurrences in every Midwest state except Ohio. On the 10th, an EF3 tornado injured eight people near Mayfield, Kentucky and other tornadoes that day caused structural damage to buildings. Two tornadoes on the 24th touched down in Upper Michigan (Marquette County) where tornadoes are less frequently reported. Damage was largely limited to trees.
 

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The Iowa Climatology Bureau also contributed to this report.
The Minnesota State Climatology Office also contributed to this report.
The Missouri Climate Center also contributed to this report.