May 2022 Weather and Its Impacts on Missouri

Pat Guinan
State Climatologist
University of Missouri Extension

May temperatures in Missouri were erratic with alternating periods of warm and cool weather, including a highly unusual heatwave from May 9-14^th, Figure 1. Preliminary data for the state indicates a warmer than normal month, with an average statewide temperature of 65.8°F, or 1.6°F above normal, Figure 2. It was the second above average month for the year, Figure 3.

An extraordinary spring heatwave impacted much of the central U.S., from Texas to Michigan, during the second week of May, Figure 4. Hundreds of records were reported in the region, with preliminary data indicating 172 records broken in Missouri during the 6-day period, Figure 5. Columbia Regional Airport set maximum temperature records for 6 consecutive days. High humidity accompanied the record warmth and led to record heat indexes for the time of year. Using hourly temperature and relative humidity data since 1970, Columbia, MO reported heat indexes ≥95°F for 16-hours between May 9-11, 2022, which is the earliest time of year when heat indexes reached that threshold, Figure 6.

Preliminary data for the spring season (Mar-Apr-May) indicate an average temperature of 55.0°F, or 0.9° above the long-term average. Mild March and May temperatures offset below average conditions during April. Over the past 25 years, there have been only five cooler than average springs, Figure 7.

May precipitation was variable across Missouri but averaged above normal for the state. Preliminary data indicate a statewide average total of 6.29 inches, or 1.63 inches above the long-term average. The wet conditions mimic the trend over the past 33 years. Since 1990, 23 Mays, or 70% of them, have been wetter than average, Figure 8. Four out of the five wettest Mays on record have occurred since 1990. Wetter than average months have been dominant since the start of 2022, where four out of the past five months have been wetter than average, Figure 9.

May precipitation varied across the Show Me State, with below average rainfall reported across much of northern Missouri as well as some pockets in southeastern sections. According to radar estimates, some localized areas of northern Missouri reported 2.5-3.5 inches for the month, Figure 10. Parts of west central, southwestern and south central Missouri reported more than 10-inches for May. Most locations around the state reported 5-7 inches for the month. The highest and lowest monthly rain gauge reports were 14.67" near Monett (Lawrence Co.) and 2.54 inches at Kirksville Regional Airport (Adair Co.).

Preliminary precipitation data for the spring season indicate a statewide average total of 15.18" or 3.34 inches above the long-term average. It was the fourth consecutive wetter than average spring for the state, Figure 11. Precipitation for 21 out of the past 33 springs (64%) has been above average.

According to the Missouri Agricultural Statistics Service, as of May 29, 2022, 91% of the corn and 52% of the soybean crop had been planted; the 5-year average is 89% and 49%, respectively. Weather conditions generally benefited pastures with 58% of them reported to be in good condition and 10% excellent. Hay supplies and other roughages were listed at 86% adequate and 3% surplus. Stock water supplies were reported mostly adequate at 85% and 15% surplus. Topsoil moisture supplies were mostly adequate (76%) to surplus (23%) statewide. Subsoil moisture supplies were mostly adequate (85%) to surplus (13%).

As of May 31, 2022, the U.S. Drought Monitor map indicated no drought or abnormally dry conditions in Missouri, Figure 12.

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Source: Pat Guinan, 573-882-5908