October 2020 Weather and Its Impacts on Missouri

Pat Guinan
State Climatologist
University of Missouri Extension

Preliminary data indicate the statewide average October temperature was 53.5℉, or 3.5℉ below the long-term average. It was the second consecutive year with cool October conditions and the coldest October since 2009, Figure 1. It was also the fifth below average month for the year and the third consecutive month with below average temperatures, Figure 2.

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 preliminary precipitation total for October was 3.72 inches, or 0.51 inches above the long-term average. It was the 4th consecutive October with wetter than average conditions, Figure 3. 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. It was the 6th wetter than average month for the year, Figure 4.

Measurable snow in Missouri during October is unusual, but it does occur, and this year was no exception. A winter-like event impacted the northern half of Missouri on Oct 26-27 where amounts ranged from a trace to 2-inches, Figure 5, and west central portions reported the heaviest amounts, Figure 6. Earliest measurable snowfall dates for locations with extensive snowfall records (>100 years) are listed in Table 1. Measurable snowfall is defined as =0.1 inches.

Missouri Earliest Measurable Snowfall
Location Date
Snowfall (in)
Springfield Oct 17, 1898 1.0
Kansas City Oct 17, 1898 3.3
Columbia Oct 23, 1917 0.2
St. Louis Oct 20, 1916 0.1
Table 1.

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. Drier conditions were also emerging across the northern half of the state, according to the U.S. Drought Monitor map from November 3, 2020, Figure 7.

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Missouri Average October Temperature 1895-2020*

Figure 1.

Missouri Monthly Temperature Departure from Average* Jan 2019 - Oct 2020**

Figure 2.

Missouri Average October Precipitation 1895-2020*

Figure 3.

Missouri Monthly Precip. Departure from Average* Jan 2019 - Oct 2020**

Figure 4.

Columbia, MO snowfall Oct 26, 2020

Figure 5. Columbia, Missouri snowfall, October 26, 2020

Accumulated Snowfall (in) Oct 26-27, 2020

Figure 6.

Drought Monitor Missouri November 3, 2020

Figure 7.

Average Temperature (°F): Oct 01, 2020 to Oct 31, 2020

Average Temperature (°F) Departure: Oct 01, 2020 to Oct 31, 2020

Accumulated Precip (in): Oct 01, 2020 to Oct 31, 2020

Accumulated Precip (in) Departure: Oct 01, 2020 to Oct 31, 2020

Source: Pat Guinan, 573-882-5908