Missouri 2018 Growing Season Climate Summary
MU Extension/State Climatologist
Commercial Agriculture Program
November 12, 2018
It was a challenging growing season for Missouri producers in 2018 beginning with highly unusual spring temperature anomalies followed by summer heat and drought.
A persistent upper air weather pattern brought unseasonably cold temperatures to much of the north central U.S. during the first 3 weeks of April. A pool of cold air spinning over Hudson Bay pumped reinforcing shots of arctic air into the region, leading to record temperatures and several snow events for the month. Temperature departures averaged more than 10 degrees below normal for the 3-week period. Preliminary data for Missouri indicate the statewide average temperature for April was 48.2°F, or 6.6 degrees below the long-term average. The month ranked as Missouri's 2nd coldest April on record, only April 1907 was colder.
Most locations in Missouri experienced drier than average conditions during April. The statewide average precipitation total was 2.03 inches, or two-inches below the long-term average. It was the driest April since 2000.
The cold weather initially delayed fieldwork activity, with wetter conditions in the Bootheel also slowing progress, but drier, warmer weather during the last week of April, led to more planting opportunities. By the end of the month, only 6% of the corn had emerged, compared to the 5-year average of 22%.
The cold spring weather also hindered grass growth, and hay supplies continued to be depleted since last year's autumn drought limited pasture growth and many producers were forced to feed hay early. According to the Missouri Agricultural Statistics Service, 63% of the hay supplies and other roughages were considered in short to very short supply by the end of April.
Record May warmth impacted Missouri with data indicating a statewide average temperature of 72.5°F, or 8.2 degrees above the long-term average. A stubborn ridge of high pressure over the middle part of the country resulted in a persistent and unusually warm weather pattern. The unprecedented warmth eclipsed the prior record established in May 1962. Most locations were above normal every day of the month. Numerous states reported their warmest May on record.
The extreme flip in consecutive monthly temperature anomalies, from 2nd coldest April to 1st warmest May, was nothing short of incredible. It was an unprecedented event where Missouri essentially skipped over the spring season, April behaved like March and May was typical of June. The last time a flip in extreme temperature anomalies for consecutive months occurred in Missouri was December 1989 (3rd coldest) to January 1990 (3rd warmest).
Several locations in Missouri established daily high temperature records, especially during the last week of May. Highly unusual triple-digit heat was reported in a few northwestern Missouri communities from May 26-28.
Precipitation data indicate a statewide average May total of 4.17 inches, or 0.59 inches below the long-term average. It was the second consecutive dry month this spring. Drought conditions persisted across northern Missouri including a pocket of severe drought impacting portions of DeKalb, Daviess, Clinton and Caldwell Counties. The dryness is intense in some sections with significant deficits accumulating over the past 13 months. The St. Joseph Airport reported 23.13 inches between May 1, 2017 and May 31, 2018; normal is 40.90 inches.
Groundwater across northern Missouri is mineralized and unusable, and residents and livestock rely on surface supplies. Water shortages were reported, including water restrictions for the communities of Cameron, Hamilton and Milan. The reservoirs at Cameron and Grindstone were reported to be at 49% capacity. Additionally, a dry soil profile was affecting row crops, which were beginning to show signs of drought stress across the driest areas.
Unusually warm conditions persisted into June for Missouri with data indicating a statewide average temperature of 77.4°F, or 4.4 degrees above the long-term average. It was the 8th warmest June on record and warmest June in 65 years (1953). The May-June average temperature this year was the warmest on record.
Dryness intensified during June with much of Missouri reporting below normal rainfall. It was the 3rd consecutive month with below normal precipitation and the driest April thru June period since 2012. The statewide average June rainfall total was 3.69 inches, nearly 1-inch below the long-term average.
Missouri drought conditions expanded during June with moderate to severe drought impacting much of the northern half of the state as well as moderate drought over far southwestern sections by the last week of June.
According to the Missouri Agricultural Statistics Service, for the week ending July 1, 52% and 53% of the topsoil and subsoil moisture supplies, respectively, were in short to very short condition. Corn and soybean was rated mostly good at 45% and 43%, respectively. Pasture conditions were mostly fair at 42%, but 35% of the state reported poor to very poor pastures. The majority of hay and other roughages remained low, with 74% of the state reporting short to very short supply. Stock water supplies were mostly adequate at 69% but nearly a third of the state, 31%, reported short to very short supply.
Dry weather persisted across Missouri during July and it became the worst growing season drought for the state since 2012. Conditions across portions of northern Missouri were worse than they were in 2012 according to the U.S. Drought Monitor map released at the end of the month.
Above normal temperatures dominated during the first half of July, but cooler weather during the latter half brought a brief respite to people, pets, livestock and plants. Overall, the statewide average temperature for July was 78.2°, slightly above the long-term average of 77.6°F. It was the third consecutive warmer than average month for the state.
July precipitation was variable across Missouri with a statewide average of 2.50 inches, or 1.33 inches below the long-term average. It was the 4th consecutive month with below average precipitation and the 13th driest Apr-Jul on record.
With few exceptions, most locations received below normal rainfall. Driest locations, where less than 2-inches were observed, occurred across portions of northwestern, north central, central, southwestern and southeastern Missouri. There were numerous counties experiencing pockets of localized, but intense dryness, where less than 1-inch was reported for the month. Small areas of wetter conditions were found over the far northeast corner of the state and in mid-Missouri, centered in Randolph County. A thin corridor of higher rainfall was in west central Missouri, extending from Cass to Camden Counties.
According to the Missouri Agricultural Statistics Service report from July 29, 2018, 75% of the state reported topsoil moisture supplies in short to very short condition with 25% of the state reporting topsoil moisture in adequate condition. Statewide subsoil condition was reported 78% short to very short, and 22% adequate. Corn, soybean and pasture conditions were reported at 31%, 25%, and 69% in poor to very poor condition, respectively. Only 33% of corn and 40% of soybean were reported in good to excellent condition, and 8% of pasture was in good condition, 0% excellent. The majority of hay and other roughages were short to very short (81%), as well as stock water supplies (52%).
Impacts continued to mount from the summer heat and prolonged dryness, including crop and pasture losses, livestock stress, and declining surface water supplies, especially across northern Missouri where the dryness has persisted for well over a year in places. Hydrological issues such as dry wells and stream beds, low rivers, ponds and lake levels, and water restrictions were increasingly common. The extreme conditions were adversely affecting gardens, lawns, trees and shrubs with instances of vulnerable species succumbing to water stress.
Above normal temperatures occurred during the first half of August in Missouri with generally cooler conditions for the remainder of the month due to extended cloudy periods. Data indicate the statewide average temperature for August was 76.4, or 0.3 degrees above the long-term average. It was the 4th consecutive month with above average temperatures. For the summer season (Jun-Jul-Aug), 2018 was the 17th hottest on record. More notably, the May through August average temperature was 76.1°F, or 3.3 degrees above the long-term average, making it the 3rd hottest May-August period and hottest since 1936.
A wetter pattern emerged by mid-August and persisted for the rest of the month, bringing much needed relief to drought-stricken Missouri. Data indicate a statewide average of 5.59 inches, or 1.89 inches above the long-term average. It was the first wetter than average month since March.
Typical of the summer season, August rainfall was highly variable, ranging from less than 3 inches to more than 10 inches. However, for the majority of locations, rainfall was above average. Heaviest amounts occurred over northern and southern sections. Lowest totals were confined to west central and east central Missouri and a few far south central counties, as well as northern portions of the Missouri Bootheel.
Drought impacts intensified and accumulated during the first half of August. Impacts from the prolonged growing season heat and dryness included mounting crop and pasture losses, livestock stress, and declining water supplies. Numerous cattle were being culled due to insufficient feed supplies. Wetter conditions during the latter half of August began to mitigate some of the impacts with some greening up of pastures and lawns and slight recovery in topsoil moisture and surface water supplies.
In mid-August, the U.S. Drought Monitor map showed 83% of Missouri experiencing drought. Worst conditions were impacting portions of northern, central and southwestern Missouri. Significant rain events during the second half of August led to improving drought conditions, and, by the end of August, just over 65% of the state was in drought.
According to the Missouri Agricultural Statistics Service report for the week ending September 2, 2018, nearly half the state, 48%, reported topsoil moisture supplies in short to very short condition and 66% of subsoil moisture supplies were in short to very short condition. Corn was reported 40% in poor to very poor condition compared to 9% at the same time last year. Soybean was 28% in poor to very poor condition compared to 8% last year. Pastures were rated at 54% in poor to very poor condition compared to 6% last year. Hay and other roughages were 79% short to very short, and 50% of the stock water supplies were short to very short.
Above normal temperatures dominated the Show Me State during September, especially during the middle of the month when most locations reported daily high temperatures in the upper 80's and lower 90's from September 14-20. The majority of daily September minimum temperatures were also above normal. Data indicate a statewide average monthly temperature of 71.4°F, more than three degrees above the long-term average.
Precipitation was variable across Missouri with the majority of it falling during the first half of September. Remnants of Tropical Storm Gordon impacted the southeastern half of the state on Sep 7-8. The average statewide preliminary monthly total was 3.48 inches, or 0.6 inches below the long-term average.
According to radar estimates and ground truth reports, lightest September rainfall totals occurred over portions of west central, southwestern and east central Missouri and heaviest amounts were seen over several northern and southeastern border counties. A thin corridor of heavier rainfall extended from Henry County northeastward through portions of Benton, Pettis, Cooper, Howard, Randolph and Monroe Counties.
The U.S. Drought Monitor map for the last week of September showed some improvement compared to drought conditions depicted at the end of August.
According to the Missouri Agricultural Statistics Service, as of September 30, 44% of the soybean crop was reported in good to excellent condition compared to 66% at the same time last year. The majority of hay and roughages were short (33%) to very short (43%) with 0% surplus, while 59% of the stock water supplies were adequate. Corn harvest was advancing ahead of average at 65% compared to the 5-year average of 42%. Only 27% of the pastures were reported in good (26%) to excellent (1%) condition, 38% were in poor (25%) to very poor (13%) condition. Just 40% of topsoil moisture conditions were short (29%) to very short (11%). The majority of subsoil moisture conditions were also reported to be short (30%) to very short (23%).
Anomalous autumn warmth persisted through the first 9 days of October with a notable pattern change toward cooler, below average conditions for the remainder of the month. The statewide average October temperature was 56.4°F, or 0.6° below the long-term average. It was the first below average month since April.
October conditions were wet, especially across northern sections, and portions of central and south central Missouri. The statewide average rainfall total was 4.90 inches, or 1.69 inches above the long-term average. Some northwestern and north central counties reported more than 10-inches in October, and 20 to 25 inches between mid-August and mid-October. It was the hydrological antidote to a drought which had been impacting the region for over a year. The 20+ inches received between mid-August and mid-October were similar to totals accumulated for 12-months prior to mid-August in some northern Missouri counties. By the end of October, drought conditions significantly improved statewide.
Muddy conditions, especially during the first half of October, limited opportunities for crop dry-down and harvest. Better harvest weather emerged later in the month. According to the Missouri Agricultural Statistics Service, for the week ending October 28, corn and soybean harvest was 90% and 51% complete, respectively; 7 percentage points ahead of the 5-year average for corn and 10 percentage points behind for soybean. The majority of topsoil and subsoil moisture conditions were reported adequate at 85% and 74%, respectively. Pasture conditions were mostly fair (38%) to good (31%). However, hay supplies were mostly short (32%) to very short (37%). Stock water supplies were mostly adequate (76%).
Freezing weather was reported across most of Missouri during the latter half of the October. The northern 2/3 of Missouri experienced temperatures ≤32°F in mid-October. Another freeze event during the morning of Oct 21 impacted most of the state, with the exception of the Bootheel and a handful of locations in far southwestern Missouri. The wetter October conditions, in combination with mild weather during the first half of the month, translated to notable rejuvenation of warm season grasses over parts of the state, especially southern sections.