Missouri 2015 Growing Season Climate Summary

Pat Guinan
MU Extension/State Climatologist
Commercial Agriculture Program

November 20, 2015

The 2015 growing season was an extremely challenging one for Missouri farmers, with unprecedented wet conditions from May through July transitioning to drought in September and October.

The season started with unusually mild conditions for the first few weeks of April and cooler weather toward the end of the month. Rainfall was variable across Missouri with heaviest amounts confined to east central, southeast, and far southwestern sections where 4-6 inches were common. Generally, 2-3 inches were typical across northern sections and in a small area of south central Missouri. The rest of Missouri received 3-4 inches of rainfall.

According to the Missouri Agricultural Statistics Service, spring tillage during the last week of April was 38% complete compared to 57% for the 5-year average. Only 20% of the corn crop had been planted by April 26 compared to a 5-year average of 44%. Unusually wet weather in southeastern Missouri had limited spring planting opportunities with only 16% of the corn planted as of April 26. Cooler weather during the latter half of the month precluded farmers from planting early in northern and central sections.

May temperatures were slightly above normal with warmest conditions during the first part of the month, followed by some erratic temperature swings for a couple weeks. Warmest monthly departures occurred over eastern parts of Missouri where temperatures averaged 1-2 degrees above normal. Cooler monthly temperatures, from 0-1 degrees below normal, were confined to portions of western Missouri where wetter and cloudier conditions resided.

May is climatologically Missouri's wettest month and 2015 was no exception. Rainfall was well above average with preliminary data indicating an average statewide total of 7.30 inches, or 2.53 inches above normal. Amounts varied across the state, but most locations received more than five inches for the month. Lightest amounts ranged from 4-5 inches and were common over parts of east central Missouri, especially around the St. Louis area and few small pockets in north central Missouri. Five to eight inches were reported across much of the rest of the state, and heaviest amounts in excess of 10 inches were reported over several western counties and a few southern locations.

The wet May conditions limited fieldwork activity and planting opportunities across the state. According to the Missouri Agricultural Statistics Service, 87% of the corn and only 23% of the soybean crop had been planted by the end of May, 8% and 34% behind the 5-year average, respectively. Wettest conditions were in northwestern Missouri where only 67% of the corn had been planted as of May 31. Most of the cotton was in fair condition, still feeling the effects of some cool periods and excessive moisture earlier in the month. The wet weather benefited pastures with 72% of them reported to be in good to excellent condition at the end of May.

Soggy conditions continued into June and resulted in the wettest May-June period in two decades. Rainfall data for Missouri indicated a statewide average June total of 7.36 inches, ranking it the 9th wettest June on record, and the wettest June since 1981. Heaviest June precipitation, in excess of 10-inches, fell over much of northeastern, east central and west central Missouri. A few locations reported more than 15 inches for the month. Alternatively, portions of far southeastern Missouri, especially in the Bootheel, reported below normal rainfall for the month. Row crop irrigation was ongoing in the region where some locations reported less than 2-inches for June.

The frequency of rain events in May and June were unusually high and limited fieldwork opportunities for farmers. According to the Missouri Agricultural Statistics Service, 62% of the soybean crop had been planted as of June 28, well below the 5-year average of 94%. The chronic muddy conditions posed major challenges for farmers this year including planting crops, cutting hay, flooded fields, nutrient loss, diseases and other factors. Wheat harvest and haying opportunities were also limited.

Rainy weather continued to plague all of Missouri during July in what had become an unprecedented wet growing season for the state. The statewide monthly average of 7.93 inches made it the 4th wettest July on record, and the wettest July since 1993. Most locations received 5 or more inches during July with some counties over northern, central and southern Missouri reporting more than 10 inches. The May through July average statewide rainfall was 22.59 inches and ranked as the wettest May through July period on record for Missouri.

Missouri temperatures were seasonable during the first half of August but trended cooler during the latter two weeks. The overall statewide average temperature for the month was more than 2.5 degrees below normal and the coolest August since 2009. June through August temperatures averaged 0.5 degrees below normal; it was the third consecutive cool summer for Missouri.

August rainfall was variable across the Show Me state, ranging from mostly below normal over the northern half of the state and near to above normal over southern sections. Smaller pockets of dryness (< 1.00 inch) were confined to a few central Missouri counties. Heaviest monthly rainfall totals, ranging from 3-7 inches, were common across the southern half of the state.

Warm and dry was the September theme in Missouri with a statewide monthly temperature averaging more than 3 degrees above normal and monthly precipitation nearly two inches below normal. It was the warmest September in a decade and the driest since 2004. Despite the wettest May-July on record, dry August and September conditions were beginning to show impacts across parts of the state. Pasture growth was hindered and grasses were beginning to brown. By the end of September, the Drought Monitor map indicated abnormally dry conditions over much of central and northeastern Missouri, and smaller pockets of dryness beginning to emerge over far south central and southeastern sections.

The dryness intensified across Missouri in October with many locations reporting less than 0.25" during the first three weeks of the month. Impacts were becoming notable with increasing reports of grass fires and vegetative stress. According to the Drought Monitor map for October 27, abnormally dry conditions were impacting much of the state and moderate drought was covering much of northeastern and central Missouri. Fall pasture growth continued to struggle due to the dry conditions and could burden livestock producers in finding sufficient hay supplies to meet nutritional demands for their cattle as winter approaches.

On a positive note, the dry conditions provided ample opportunities for crop dry-down and harvest. According to the Missouri Agricultural Statistics Service, corn and soybean harvest was 97% and 80% complete, respectively, for the week ending November 2. This was 20 percentage points ahead of the 5-year average for corn and 19 percentage points of the 5-year average for soybean.

Autumn warmth persisted into October and hastened maturity of late planted soybean. The first freeze impacted parts of eastern Missouri on the morning of October 18th when temperatures dropped to the upper 20's and lower 30's. Unusually early freeze conditions were reported over parts of far southeastern Missouri during the morning of October 18th. Another more widespread light freeze impacted much the rest of the state on October 30 and 31.