Above Normal Temperatures

Annual averaged temperatures in the Midwest were well above normal. The region as a whole averaged 1.8°F above normal ranking it as the 8th warmest year (records began in 1895). All nine Midwest states ranked among the warmest 10 percent (top-12) of their records with each ranking between 5th and 12th (Figure 1). January (9th), February (2nd), and April (12th) ranked among the warmest 10 percent for the region as a whole, with six, nine, and eight states likewise ranked among the warmest 10 percent in those respective months. New record high average temperatures in April were set at some stations with very long histories in Kentucky (Louisville and Lexington, both with records back to 1872) and Ohio (Akron 1887, Cleveland 1871, and Columbus 1878). The old April records at Columbus, Louisville, and Lexington were from 1896, more than 120 years ago. August was notably cool with three states ranking among the coolest 10 percent of their records — Illinois 10th, Iowa 8th, and Missouri 7th. Warmth in September had Michigan and Wisconsin ranked among the warmest 10 percent. Following a hot and humid spell in mid-July, there was a cool 6-week period that extended into early September. Temperatures in the latter half of September were, for many Midwest locations, the hottest of the year. Chicago had a string of seven consecutive record high days, September 20th-26th, each with maximum temperatures above 90°F. December was generally warm for the first three weeks but then around Christmas temperatures fell to much below normal. The last seven days of the year were the coldest of the season, and for most locations the coldest of 2017. Temperatures dropped to -40°F in northern Minnesota and to 0°F as far south as Missouri and Kentucky. The 7-day period had average minimum temperatures below 0°F for most of the northern half of the region.

Variable Precipitation

Precipitation was generally on the wet side (ranked 27th wettest since 1895) in 2017 for the Midwest but there was a lot of variability (Figure 2). Michigan had its wettest year, and Ohio (7th) and Wisconsin (8th) also ranked among the wettest years while Illinois, Iowa, and Missouri were below normal. In February, Illinois and Missouri ranked among the driest 10 percent. From April through November, each month except September had at least one state ranked among the wettest 10 percent in their history. There were a total of 15 cases of a state with a monthly value among the wettest 10 percent during these months with all nine states having at least one. Missouri in April and Michigan in October set records for the wettest month. Tecumseh, MO (period of record, 1942-present) received 17.48 inches of precipitation in April, breaking the previous monthly precipitation record of 14.43 inches set in 1957. In September, the remnants of Hurricane Harvey brought heavy rains to Kentucky in the first few days of the month while three states (Illinois, Michigan, and Missouri) ranked among the driest 10 percent. More dry months were recorded in November (Missouri ranked 11th driest) and December (Iowa 5th and Illinois 7th). Spring ranked as the 6th wettest for the Midwest while the fall saw numerous extremes of both wet and dry.

Isolated Drought Conditions

Drought in the Midwest during 2017 was limited in areal coverage but still intense in a few locations. The year began with moderate drought mostly in Missouri (Figure 3). Drought expanded to a peak at 13 percent of the Midwest in March before spring rains wiped out all Midwest drought (Figure 4). In early May, there was no drought and no abnormally dry areas in the region for the first time since May of 2002. Late summer and fall saw new drought development around the region with southern Iowa having extreme drought from mid-August to early October. Areal coverage peaked at about 12 percent of the region in early October when scattered areas of drought touched every Midwest state except Kentucky. In the last three months of 2017, drought expanded in Missouri and neighboring parts of Iowa and Illinois while ending in other parts of the Midwest except in north central Minnesota.

Below Normal Snowfall

Seasonal snowfall for the winter of 2016-17 was well below normal for much of the region. The only above-normal areas were in northwestern Minnesota and a swath from north central Iowa to northeastern Wisconsin. The southern half of the Midwest had seasonal totals ranging from 10 to 50 percent of normal. It was a slow start to the 2017-18 snow season overall. The first significant snow of the season fell in late October in northern Minnesota and the Upper Peninsula of Michigan with totals up to a foot. There was little snowfall in November. Lake-effect snows began in earnest in early December as the nearly ice-free and relatively warm Great Lakes provided ideal conditions. Heavy snow fell down wind of the lakes through mid-December and then again in the last week of the year. Away from the Great Lakes, in southern Minnesota through southern Wisconsin, seasonal snowfall deficits topped 10 inches. A number of lakes in southern and central Minnesota froze in November but then melted again. Most Minnesota lakes were frozen over by mid-December.

Late Spring Freeze, Early Fall Freeze for Some

There was a late freeze in northern and eastern parts of the Midwest in May. Freezing temperatures touched all Midwest states except Missouri. Temperatures fell below 25°F in Minnesota, Wisconsin, and Michigan with reports of damage to fruit trees in Michigan. An early freeze on August 25th in the Arrowhead of Minnesota and the Upper Peninsula of Michigan, brought the growing season to an early end.

Total Solar Eclipse

The total solar eclipse on August 21st was the first to pass across the Midwest since 1925. The path of totality crossed Missouri, southern Illinois, and western Kentucky and the remainder of the region had a partial eclipse. Viewing in the Midwest was generally good but a frontal boundary limited viewing for parts of Iowa, Minnesota, Wisconsin, and northern Illinois.

Widespread Flooding in April

Heavy rains in the southern Midwest in late April, brought widespread flooding. Southern Missouri was very hard hit with locations picking up more than 10 inches of rain in just two days. Interstate 44 was closed after parts of the roadway were washed away by floodwaters. Four deaths and more than 100 rescues were related to flooding in southern Missouri. Many Midwest corn and soybean fields had ponding or saturated soils that caused many acres to be replanted.

Deadly Tornadoes

There were four deadly tornadoes in 2017 with five deaths. Two tornadoes in Illinois killed three on February 28th, another in Missouri the same day killed one, and a Wisconsin tornado on May 16th was responsible for 1 death and 25 injuries. Iowa had a busy day early in the year, with 18 tornadoes on March 6th. On November 5th, 21 Midwest tornadoes included 17 in Ohio alone. The Ohio tornado count for the day was nearly equal to the average annual total of 20 tornadoes.

Wind Event

Non-thunderstorm winds were deadly in three other cases in 2017. On March 8th, two deaths were caused when high winds blew down a tree onto a vehicle. On May 17th, strong winds in Missouri downed a rotten tree killing one person and in central Illinois died in a multiple vehicle accident caused by low visibility in a dust storm.