Missouri 2012 Growing Season Climate Summary

Pat Guinan
State Climatologist
Commercial Agriculture/University of Missouri Extension

November 12, 2012

An extremely challenging year was faced by farmers in 2012 when a historic drought emerged early in the growing season and persisted into summer. More than 2/3 of the country was immersed in drought as summer progressed, a situation not experienced in nearly 60 years. For much of the growing season, Missouri and Kansas were the epicenter of the drought, with severe to exceptional drought conditions stretching from Utah to Indiana in July and August, according to the National Drought Mitigation Center's Drought Monitor map. Missouri's first form of widespread relief occurred on the last day of August when remnants of a tropical system brought significant rainfall to much of the state. Unfortunately, by then, significant drought damage had occurred.

The growing season got off to a good start for producers when record warm March temperatures were followed by mild and dry weather in April. These conditions provided numerous opportunities for early spring planting, some at record pace. According to the Missouri Agricultural Statistics Service, 75% of the corn was planted toward the end of the April, which was 3 weeks ahead of normal. Unusually dry conditions had evolved over the Bootheel region and parts of west central Missouri in April, but there was optimism for a wetter pattern setting-up in May, typically Missouri's wettest month.

Unfortunately, a wet regime did not emerge in May and an unusually dry, warm and sunny period impacted the state for much of the month. Some locations in northeast, central and east central Missouri went 24 consecutive days (May 8-31) with less than 0.10 inches of rain. Some of the lowest monthly totals were in southeastern Missouri where Perryville and Poplar Bluff reported 0.40" and 0.30", respectively. Only a handful of counties reported more than 5 inches for the month, which is near average for May.

Numerous sunny days in May and June, coupled with above normal temperatures and below normal relative humidity, led to unusually high moisture loss from soils, water surfaces and vegetation. The high evaporative losses, in combination with lack of rainfall, resulted in a "flash drought" across the state as agricultural and horticultural impacts rapidly emerged. Reports of deteriorating pastures, declining soil moisture reserves, limited stock water supplies, and crop stress increased significantly as May progressed. Homeowners' lawns began turning brown and irrigation was going at a summer like pace in many locations.

May 2012 ranked as the 7th driest May on record for Missouri (tied with 2005), with a statewide average total of 2.25 inches, or nearly 3-inches below normal. It was also Missouri's 4th warmest May on record, and warmest May since 1987. A seasonal temperature record for spring was also established with a March through May average temperature of 62°F, smashing the previous record spring warmth, set in 1977, by an incredible 3 degrees F.

By the end of June, one of the worst droughts in nearly 25 years was impacting Missouri and agricultural crops were feeling the stress from lack of rain and sweltering temperatures. Precipitation data indicate June 2012 was the 6th driest June on record for Missouri and the driest since 1988. Statewide average June rainfall was less than two inches, or nearly 3 inches below normal. The combined May-June average rainfall for the state was 4.20 inches, ranking it the 6th driest May-June period on record and the driest since 1988. Extreme heat during the last week of June exacerbated the stressful conditions with many locations reporting triple digit heat and record temperatures. The last time Missouri experienced 100-plus degree heat in June was 1988. On June 28th, several communities reached all-time high temperature records for the month of June including St. Louis, Columbia, Rolla, and West Plains with 108, 107, 106 and 106°F, respectively.

Grass fires increased during June and burn bans were imposed across the state. Toward the end of the month, a forest fire in the Mark Twain National Forest burned 600 acres in Iron County. According to the Missouri Agricultural Statistics Service, by the end of June, 97% and 93% of the topsoil and subsoil moisture supplies, respectively, were in short to very short condition. Nearly half of the corn and soybean crop was reported to be in poor to very poor condition, and is the highest percentage for the time of year since 1988. Pasture condition had declined to 76% poor to very poor, and hay and stock water supplies were also declining with more than half in short to very short condition.

Unrelenting dryness and extreme heat persisted through July. The average statewide temperature for the month was 83.7°F, or 6.4°F above normal. It was the hottest July for Missouri since 1980. July rainfall was paltry for the state, with a statewide average total of 1.67 inches, or 2.57 inches below normal for the month. It was the 9th driest July on record, and the driest July since 1970. Generally, west central and southwestern Missouri received the least amount of rain, with less than 0.50 inches reported in many locations. Several counties in far southwestern Missouri reported less than 0.25 inches for the month. Some localized and scattered thunderstorm events brought heavier rainfall to other areas of the state, including parts of south central, southeast and north central Missouri where 2-4 inches were reported.

Drought impacts continued to mount in July including widespread crop and pasture losses, livestock stress, and declining stock water and hay supplies. Hydrological issues such as dry wells and stream beds, low river levels, and rural and urban water restrictions were increasingly common. Even with burn bans in place, grassfires and forest fires were reported. The extreme conditions were adversely affecting gardens, lawns, trees and shrubs with numerous instances of vulnerable species succumbing to water and heat stress. Wildlife was impacted by the lack of healthy vegetation and dwindling water resources.

By the end of July, and according to the National Agricultural Statistics Service, Missouri had the distinction of having the worst corn, soybean and pasture conditions in the United States. Corn, soybean and pastures were reported to be in 83%, 72%, and 98% poor to very poor condition, respectively. Soil moisture reserves were abysmal with 99% of the topsoil and subsoil reported in short to very short condition. Hay and stock water supplies were well below normal and reported to be in 86% and 91% short to very short condition, respectively.

It was also the 3rd warmest and 3rd driest May through July period on record for Missouri. Only May-July 1934 and 1936 were warmer and May-July 1901 and 1936 were drier.

The historic drought impacting Missouri intensified over portions of the Show Me state in August where, according to the 8/28/2012 Drought Monitor map, 97.44% of the state was in extreme or exceptional drought. Significant and widespread moisture relief was not realized until the remnants of Hurricane Isaac moved northward from Louisiana and Arkansas into southern Missouri on the last day of August. Much of the state reported substantial precipitation from Isaac over Labor Day weekend.

The statewide precipitation average for August was 2.35 inches, or 1.3 inches below normal. Lowest August totals were concentrated across central Missouri where many locations reported less than 1-inch for the month. Prior to Isaac, portions of Missouri were recipients of significant rain events and brought temporary drought relief. Most notably, rain impacted southwestern, south central, east central and northwestern sections. Precipitation enveloped a large part of Missouri on 8/31 as Isaac remnants spiraled northward into the Show Me state. The tropical depression lingered in Missouri for much of Labor Day weekend and brought widespread drought relief in the form of a steady rain falling over multiple hours.

Average statewide precipitation for the summer period, Jun-Jul-Aug, was 5.97 inches and ranked as the third driest summer on record, and driest summer since 1953.

Cooler September temperatures in Missouri, in combination with rain events, mitigated the drought conditions impacting the state, but by no means eliminated it. Preliminary temperature data indicate a statewide average temperature of 66.7°F, or slightly less than 1 degree F below normal. The cooler than normal month broke a string of 11 consecutive months with above normal temperatures for Missouri. Preliminary rainfall data for September indicated an average statewide total of 5.23 inches, nearly 1-inch above normal, and only the second time this year, following March, when a month recorded above average rainfall. Heaviest September totals fell across southern Missouri where 5-7 inches were typical. Some of the lowest September amounts were in far northern and northwestern sections, where 1-2 inches were common.

Varying periods of warm and cool weather, and the lack of any widespread killing freeze for most of October, allowed additional vegetative growth and green-up of lawns and pastures across the state. Topsoil moisture conditions improved across southwestern, south central and northeastern sections where above normal rainfall totals of 4-6 inches were common. Below normal October rainfall occurred over northwestern, west central and a few southeastern counties, where less than 2-inches were reported for the month. Long-term severe and extreme drought conditions were still impacting northwestern, central and far southeastern Missouri toward the end of October, where year-to-date deficits were 8-12 inches. Significant surface water recovery was especially notable over southwestern sections where more than 10 inches of rain fell between September-October.

Even though overall drought conditions have improved across Missouri this fall, a complete recharge of water resources above and below the ground was not realized by the end of October. According to the October 28th, 2012 Missouri Agricultural Statistics report, 46% of topsoil moisture in the state was in short to very short supply, and 79% of the subsoil moisture supply was reported short to very short. Additionally, 78% of the stock water supplies were reported to be in short to very short supply and 60% of the pastures were in poor to very poor condition.

The highest likelihood for hydrological drought to carryover into next year exists across northwestern Missouri, where a significant precipitation deficit remains and precipitation is climatologically the lightest between November and February. Normal Missouri precipitation from November to February ranges from 4-6 inches in the northwest corner to 16-18 inches in the Bootheel.