Missouri Climate can be a-MAY-zing

Pat Guinan
State Climatologist
Commercial Agriculture/University of Missouri Extension

Weather and climate has fascinated me since early childhood days while growing up on a farm in central Illinois. My father would pay attention to the local weather forecasts and check the rain gauge religiously. He did all the right things to be a good farmer, but it was the weather he had no control over and that must have been maddening. At the age of 14, I purchased a max/min thermometer and rain gauge and set them up in the backyard. I began making daily weather observations and, over time, established a climatology for the area.

Little did I know that my childhood interests would mature into an adult profession. Missouri climatology fascinates me, and I have learned much about our weather and its variability over the years. For the most part, it is benign and uneventful, but weather records have shown that sometimes the weather can be far from plain and ordinary. Whenever extraordinary weather events occur, I get a flurry of inquiries. Is this normal? Is our climate changing? Generally, my response is to put the anomaly into perspective and resort to examples of similar situations that occurred 20, 50 or 100 years ago.

Missouri climate records reveal a lot about our weather history. Some locations in Missouri have climate records that began over 160 years ago. St. Louis weather records, for example, began in 1837. Abnormal events can be found throughout the climate history, and so my best explanation for unusual weather phenomena is that it is a part of the variability that exists within our climate system.

There have been numerous amazing weather events in Missouri during May. To name a few:

Snow in May? On May 3, 1907, 4-8 inches of snow blanketed portions of northwestern Missouri. Fairport, in Dekalb County, reported 8.0 inches of the white stuff. On the morning of May 2, 1929, a snowstorm dropped 3-6 inches of snow from the Ozarks northeastward to St. Louis, MO. Heavier snowfall reports varied from 4 inches in St. Louis to 6 inches in Springfield.

Hot May? During the last 3 days of May 1934 temperatures across the state climbed into the upper 90s and 100s. Maryville, MO, reached 110°F on May 30 setting an all-time high for the state for the month.

May frost? Frost covered the entire state the morning of May 25, 1925, as temperatures dropped into the lower 30s. Louisiana, MO, bottomed out to a chilly 26°F.

Dry May? Typically, May is our wettest month in Missouri averaging 4.71", but back in 1911, the statewide average was 1.48". New Madrid, MO, established a state record minimum rainfall in May 1911 when they received a scant 0.10".

Wet May? The heavens opened in May 1943; and by the end of the month, the statewide average rainfall was 10.13". Joplin, MO, has the dubious distinction of recording the wettest May on record for the state when 25.54" fell in 1943.