Missouri 2020 Growing Season Climate Summary
MU Extension/State Climatologist
Commercial Agriculture Program
November 5, 2020
Most of Missouri experienced a favorable growing season in 2020 with the exception of southwestern sections where a localized but intense drought emerged in early summer and persisted through the first half of October, creating adverse conditions and challenges for producers in the region.
The growing season started off cool with April being nearly two degrees below average. There were alternating periods of above and below average temperatures during the month but a majority of below average daily minimum temperatures combined with a much below normal cold spell from Apr 13-17 tipped the scale toward a colder than average month.
Heavier April precipitation totals were reported across southwest, south central and east central Missouri where 4-6 inches were common. Much of northern and west central Missouri received 2-4 inches. Statewide, April precipitation was near normal with an annual statewide average of 3.95 inches.
Two unusual mid-April snow events impacted northern Missouri on April 16-17. The first event impacted far northeastern sections during the morning of the 16th. Accumulations were generally 1-4 inches and occurred mostly on elevated and grassy surfaces. The next snow event occurred the following day and impacted much of northern Missouri with 3-10 inches and heaviest amounts reported on the Missouri-Iowa border.
According to the Missouri Agricultural Statistics Service, for the week ending April 26, corn planting was 25% complete, 21 percentage points behind the 5-year average. Stock water supplies were reported mostly adequate at 94% with 84% of the hay supplies and other roughages adequate and 9% surplus. The majority of pastures, 59%, were in good condition and 29% in fair condition.
Seasonably cool temperatures were the rule in Missouri during May, especially with maximum daily temperatures. The statewide average temperature was 62.0℉, or 2.3℉ below the long-term average. It was the coolest May since 2002. It was the coolest April-May period since 2008 and only the fifth time since 1998 with below normal temperatures for the two-month period.
Unusually cool minimum temperatures, some at or below freezing, occurred on May 9 and 11 with frost reported in many locations. Lowest temperatures at some locations during these dates were at or below 30℉. Several long-term low temperature records were broken including Columbia (36℉ on May 11), Kansas City (34℉ on May 9), and Vichy-Rolla (36℉ on May 9).
May precipitation was variable across Missouri but averaged above normal for the state. The statewide average May total was 6.22 inches, or 1.45 above the long-term average. May precipitation varied across the Show Me State, ranging from less than 3-inches in some central and west central counties to more than a foot over portions of the Ozarks.
Slow moving upper level lows resulted in extended periods of cloudy weather during the month, especially between May 12-22. Using solar radiation records for Columbia, MO, it was the lowest solar May since 2013.
According to the Missouri Agricultural Statistics Service, as of May 31, 92% of the corn and 49% of the soybean crop had been planted; the 5-year average is 90% and 49%, respectively. The cool, cloudy weather generally benefited pastures with 64% of them reported to be in good to excellent condition.
Above average June temperatures were dominant for Missouri with a statewide average monthly temperature of 75.0℉, or 2.0 degrees above the long-term average. The above average temperatures followed the warm trend over the past several years, where only one June since 2005 has been cooler than average. It was also the first warmer than average month since March.
June precipitation was below average statewide, but highly variable across Missouri, ranging from over 9-inches in far northeastern sections to less than 0.50 inches in the far southwestern corner of the state. The statewide average rainfall total was 3.63 inches, a little more than 1-inch below the long-term average.
An unusual event impacted Missouri on Jun 8-9 when the remnants of an early season tropical storm named Cristobal spiraled northward through the center of Missouri and dropped significant rainfall, ranging from 1-4 inches. It was unusual not only for the time of year but also for the track it made from Louisiana, northward through Missouri, then north-northeastward into the upper Midwest.
Abnormally dry conditions began to emerge as June progressed and was impacting far western sections of the state, especially around the Kansas City area southward to the Arkansas border. A few counties south of St. Louis were also abnormally dry and moderate drought crept into portions of Jasper and Newton Counties, in far southwestern Missouri.
According to the Missouri Agricultural Statistics Service, for the week ending June 28, 7% of the corn was silking compared to a 5-year average of 17%. Soybean was 94% planted, compared to a 5-year average of 86%. Topsoil moisture supplies were rated 77% adequate to surplus and subsoil moisture was rated at 87% adequate to surplus. Corn was rated mostly good to excellent at 68% and soybean was reported at 63% good to excellent. Pasture conditions were mostly good to excellent at 66%. The majority of hay supplies and other roughages were adequate at 97%. Stock water supplies were reported to be in adequate (94%) or surplus (4%) condition.
Above average temperatures impacted Missouri in July a statewide average temperature of 79.1℉, or 1.5℉ above the long-term average. It was the second consecutive warmer than average month and fifth for the year. Daily temperatures for July were seasonably warm, but not extreme, with highest temperatures reaching the lower 90's statewide and minimum temperatures staying in the 60's and 70's.
July precipitation was above average across the state with the exception of a few areas in southwestern and south central Missouri as well as a few northeastern counties bordering Iowa and the southern tip of the Bootheel. The statewide average July total was 5.84 inches, or 2.02 inches above the long-term average.
Heaviest July rainfall occurred over portions of northwestern, west central and east central Missouri where 5-8 inches were common. Driest conditions were across parts of southern Missouri. An extreme rainfall event in west central Missouri at the end of the month was reported in St. Clair County where a CoCoRaHS observer reported nearly a foot of rain in a 24-hour period.
According to the Missouri Agricultural Statistics Service report from July 26, 2020, 26% of the state reported topsoil moisture supplies in short to very short condition with 71% of the state reporting topsoil moisture in adequate condition. Statewide subsoil condition was reported 21% short to very short, and 78% adequate. Corn, soybean and pasture conditions were reported at 7%, 7%, and 14% in poor to very poor condition, respectively. The majority of corn and soybean were reported in good to excellent condition at 73% and 69%, respectively. The majority of pasture was in good to excellent condition at 53%. The majority of hay and other roughages were adequate to surplus (90%), as well as stock water supplies (92%).
Abnormally dry to moderate drought was impacting all of southwestern Missouri as well as parts of south central Missouri and the southern tip of the Missouri Bootheel, according to the U.S. Drought Monitor map released on July 30, 2020.
Seasonably cool August temperatures impacted Missouri with a statewide average temperature of 74.2℉, or 1.9℉ below the long-term average. Near to below normal temperatures occurred during the first three weeks of August followed by warmer conditions in the final 10-days, including a few days with high temperatures in the lower and mid-90s.
Daily summer temperatures (Jun-Jul-Aug) this year reflected the overall trend for the past few decades, with no prolonged periods of extreme high temperatures. No triple-digit heat was reported in 2020 and the statewide average summer temperature was 76.1℉, 0.5℉ above the long-term average. Summer weather patterns over the past several decades indicate little change in maximum temperature trends whereas minimum summer temperatures have been warming. This phenomenon is primarily due to above average summer dew point temperatures in Missouri, which act to suppress maximum air temperature and elevate minimum air temperature.
Drier than average weather impacted Missouri in August with a statewide average of 2.94 inches, 0.76 inches below the long-term average.
Typical of the summer season, August rainfall was highly variable, ranging from less than 0.25 inches to nearly 12-inches. Radar estimates indicated pockets of more than 5-inches in parts of the state and driest areas located in some far northern counties and southwestern sections. Remnants of Hurricane Laura impacted southeastern Missouri on August 28.
According to the U.S. Drought Monitor map, for the week of August 25, 2020, abnormally dry conditions to severe drought was impacting parts of Missouri. Impacts were accumulating, with crop stress, burned-up pastures and decreasing water supplies reported in parts of southwestern Missouri where dry conditions have been ongoing since early June.
According to the Missouri Agricultural Statistics Service report for the week ending August 31, 2020, 64% of the state reported topsoil moisture supplies in adequate condition with 1% surplus, whereas 31% of Missouri reported short topsoil moisture supply and 4% very short. Subsoil moisture supplies were reported 69% adequate and 0% in surplus condition compared to 29% of the state reporting subsoil moisture supplies short and 2% very short. Corn was reported 77% in good to excellent condition compared to 38% last year. Soybean was reported 75% in good to excellent condition compared to 46% last year. Pastures were rated at 55% in good to excellent condition compared to 70% last year. Hay and other roughages were 87% adequate to surplus compared to 84% last year. Stock water supplies were 91% adequate and 9% short.
Mostly pleasant late-summer, early fall-like temperatures occurred during September with a statewide average temperature of 67.1℉, or 1.2 degrees below the long-term average. Drier than average conditions prevailed during the month with an average statewide total of 3.08 inches, 0.99 inches below the long-term average. September rainfall, however, was highly variable across Missouri with highest amounts occurring over parts of west central, central, north central, northeast and far southeastern Missouri and a dry corridor extending from east central to southwestern Missouri, generally paralleling I-44. Another area of dryness was found in far northwestern Missouri.
The U.S. Drought Monitor map for September 29, 2020 showed portions of Missouri experiencing abnormally dry conditions to severe drought. Driest conditions were located in southwestern Missouri where some counties experienced dry weather for much of the summer. Agricultural and hydrological impacts in southwestern Missouri were mounting, ranging from poor crop yields, burned-up pastures, and dry springs, creeks and ponds. Some ranchers were hauling water, but the big concern was whether hay supplies would last into next spring.
According to the Missouri Agricultural Statistics Service, as of September 28, 2020, the majority of the corn crop was in good to excellent condition at 62% and 18%, respectively. Remaining corn conditions this year were 16% fair, 3% poor and 1% very poor. Corn harvest was behind schedule at 21% compared to the 5-year average of 41%. The majority of the soybean crop this year was also reported in good (61%) to excellent (20%) condition compared to 44% good and 6% excellent at the same time last year.
The majority of hay and roughages were adequate (76%) to surplus (14%) this year with 7% short and 3% very short. Stock water supplies were mostly adequate at 91%, with 8% short and 1% very short. The majority of pastures were reported in good (47%) to excellent (7%) condition while 12% were in poor or very poor condition. The majority of topsoil moisture conditions were adequate (73%) and 0% surplus while 24% were reported short and 3% very short. The majority of subsoil moisture conditions were also reported to be adequate (76%) to surplus (0%) with 21% short and 3% very short.
A couple frosty mornings occurred during the first week of October over parts of Missouri, with a few locations in northern sections and the eastern Ozarks dropping into the upper 20's and lower 30s. Overall, however, weather conditions were seasonably mild and dry during the first half of the month. A major pattern change occurred mid-month and much cooler and wetter weather dominated the rest of October. Most locations, with the exception of the Missouri Bootheel and dense urban population centers, experienced their first fall freeze by the morning of October 16, effectively bringing an end to the growing season. The statewide average October temperature was 3.5 degrees below the long-term average.
The statewide average precipitation total for October was around 3.5 inches, near the long-term average. However, precipitation was highly variable and the majority of it fell during the latter half of the month. Monthly amounts ranged from 0.50 to 1.5 inches across the northern third of the state, 1.5 to 4.5 inches over the central third, and 4.5 to 8.0 inches over the southern third of Missouri. A few southern counties reported more than 9-inches including locations in Taney, Douglas, Scott and Mississippi Counties.
Excellent harvest weather during the first couple weeks of October transitioned to limited opportunities for crop dry-down and harvest with the cool, wet conditions during the latter half of the month. Crop harvest was running slightly behind normal by the end of October. According to the Missouri Agricultural Statistics Service, for the week ending November 2, corn and soybean harvest was 80% and 60% complete, respectively; 7 percentage points behind the 5-year average for both crops. The majority of topsoil and subsoil moisture conditions were reported adequate at 69% and 68%, respectively. Hay supplies were mostly adequate (73%) to surplus (10%) with only 13% reported short to 4% very short. Stock water supplies were mostly adequate (81%).
It's important to note that wetter conditions in drought-affected southwestern Missouri mitigated water supply concerns during the last couple weeks of October but the rainfall came too late for renewed grass growth and concerns remained with availability of livestock winter feed supplies.