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What is Harristown, IL, Weather Like in October?

During the month of October, Harristown, IL, has an average daytime high temperature of 66°F and an average overnight low temperature dropping to 46°F. Around 3.41 inches of precipitation is received during the month, with about 34.83 inches falling in a typical year. As you might expect, snow is not common in the month of October. Annually, Harristown receives around 9.70 inches of snow.

October 2025: Actual vs. Average Temperatures

Showing temperatures through today (October 19, 2025)
Actual High Average High Actual Low Average Low

Actual data from: PWS_MOSERFARM

Harristown, IL Daily Weather Averages for October

Recorded at Decatur Wtp (usc00112193), 7.3 miles ESE of Harristown, IL
Day Avg Temps (°F) Precip (in) Snow (in) Degree Days (°F)
Low High Mean Month Year Month Year Heat Cool
10/1 51 F 72 F 62 F 0.09" 31.51" 0.00" 9.70" 5.2 F 1.9 F
10/2 51 F 72 F 61 F 0.19" 31.61" 0.00" 9.70" 5.5 F 1.7 F
10/3 50 F 71 F 61 F 0.29" 31.71" 0.00" 9.70" 5.7 F 1.6 F
10/4 50 F 71 F 61 F 0.39" 31.81" 0.00" 9.70" 6 F 1.5 F
10/5 50 F 71 F 60 F 0.50" 31.92" 0.00" 9.70" 6.3 F 1.4 F
10/6 49 F 70 F 60 F 0.60" 32.02" 0.00" 9.70" 6.6 F 1.3 F
10/7 49 F 70 F 59 F 0.71" 32.13" 0.00" 9.70" 7 F 1.2 F
10/8 49 F 69 F 59 F 0.81" 32.23" 0.00" 9.70" 7.3 F 1.1 F
10/9 48 F 69 F 59 F 0.92" 32.34" 0.00" 9.70" 7.6 F 1 F
10/10 48 F 68 F 58 F 1.03" 32.45" 0.00" 9.70" 7.9 F 1 F
10/11 48 F 68 F 58 F 1.13" 32.55" 0.00" 9.70" 8.2 F 0.9 F
10/12 47 F 67 F 57 F 1.24" 32.66" 0.00" 9.70" 8.5 F 0.8 F
10/13 47 F 67 F 57 F 1.35" 32.77" 0.00" 9.70" 8.8 F 0.7 F
10/14 46 F 66 F 56 F 1.46" 32.88" 0.00" 9.70" 9.2 F 0.6 F
10/15 46 F 66 F 56 F 1.57" 32.99" 0.00" 9.70" 9.5 F 0.5 F
10/16 46 F 65 F 56 F 1.69" 33.11" 0.00" 9.70" 9.9 F 0.4 F
10/17 45 F 65 F 55 F 1.81" 33.23" 0.00" 9.70" 10.2 F 0.4 F
10/18 45 F 65 F 55 F 1.93" 33.35" 0.00" 9.70" 10.6 F 0.4 F
10/19 45 F 64 F 54 F 2.05" 33.47" 0.00" 9.70" 11 F 0.4 F
10/20 44 F 64 F 54 F 2.17" 33.59" 0.00" 9.70" 11.4 F 0.3 F
10/21 44 F 63 F 54 F 2.28" 33.70" 0.00" 9.70" 11.8 F 0.3 F
10/22 44 F 63 F 53 F 2.40" 33.82" 0.00" 9.70" 12.3 F 0.3 F
10/23 43 F 62 F 53 F 2.51" 33.93" 0.00" 9.70" 12.7 F 0.3 F
10/24 43 F 62 F 52 F 2.62" 34.04" 0.00" 9.70" 13.1 F 0.2 F
10/25 43 F 61 F 52 F 2.74" 34.16" 0.00" 9.70" 13.5 F 0.2 F
10/26 42 F 61 F 51 F 2.85" 34.27" 0.00" 9.70" 13.9 F 0.2 F
10/27 42 F 60 F 51 F 2.96" 34.38" 0.00" 9.70" 14.3 F 0.2 F
10/28 41 F 60 F 50 F 3.08" 34.50" 0.00" 9.70" 14.8 F 0.2 F
10/29 41 F 59 F 50 F 3.19" 34.61" 0.00" 9.70" 15.2 F 0.2 F
10/30 41 F 58 F 50 F 3.30" 34.72" 0.00" 9.70" 15.6 F 0.1 F
10/31 40 F 58 F 49 F 3.41" 34.83" 0.00" 9.70" 16.1 F 0.1 F

Weather data provided by Xweather