September weather in Sullivan, IL
The average temperature in Sullivan in September is 67.3°F (54.6°F–80.1°F). Average precipitation: 2.71 inches.
September is a fall month in Sullivan, and is warmer than the annual average of 53°F. Daily temperatures swing about 25.5°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 12h 15m. For travel, September is a comfortable month to visit.
Avg High
80.1°F
Avg Low
54.6°F
Precipitation
2.71 in
Daylight
12h 15m
September records in Sullivan
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 96.1°F (2013) | 46.0°F (2009) | 1.66 in (2012) |
| September 2 | 98.1°F (2011) | 46.0°F (2009) | 1.48 in (2010) |
| September 3 | 97.0°F (2002) | 46.9°F (2009) | 3.30 in (1993) |
| September 4 | 97.0°F (2011) | 48.9°F (2003) | 1.50 in (2022) |
| September 5 | 93.9°F (2007) | 46.9°F (2003) | 1.95 in (1994) |
| September 6 | 93.0°F (2015) | 45.0°F (2011) | 1.16 in (2012) |
| September 7 | 93.9°F (2002) | 45.0°F (2011) | 1.34 in (1945) |
| September 8 | 93.0°F (2002) | 45.0°F (2017) | 1.09 in (2021) |
| September 9 | 91.9°F (2005) | 46.0°F (2017) | 1.50 in (1950) |
| September 10 | 93.9°F (2013) | 46.0°F (2017) | 1.15 in (1991) |
| September 11 | 95.0°F (2013) | 45.0°F (2017) | 2.20 in (2014) |
| September 12 | 93.0°F (2013) | 44.1°F (2007) | 1.00 in (1951) |
| September 13 | 91.9°F (2019) | 39.0°F (2014) | 2.02 in (1945) |
| September 14 | 91.9°F (2005) | 37.9°F (2014) | 1.40 in (1993) |
| September 15 | 91.9°F (2018) | 37.0°F (2007) | 2.00 in (2008) |
| September 16 | 91.0°F (2018) | 37.0°F (2007) | 1.05 in (2014) |
| September 17 | 93.0°F (2018) | 43.0°F (2014) | 0.87 in (2016) |
| September 18 | 93.9°F (2018) | 43.0°F (2014) | 1.27 in (1982) |
| September 19 | 93.0°F (2018) | 37.9°F (2020) | 0.71 in (1942) |
| September 20 | 91.0°F (2018) | 39.9°F (2006) | 1.30 in (1950) |
| September 21 | 93.0°F (2017) | 39.9°F (2006) | 1.06 in (1947) |
| September 22 | 95.0°F (2017) | 39.9°F (2006) | 0.86 in (2021) |
| September 23 | 93.9°F (2005) | 41.0°F (2002) | 2.32 in (1993) |
| September 24 | 93.0°F (2017) | 33.1°F (2012) | 1.37 in (2024) |
| September 25 | 93.0°F (2017) | 34.0°F (2012) | 0.76 in (2000) |
| September 26 | 91.0°F (2017) | 42.1°F (2001) | 1.81 in (2005) |
| September 27 | 91.9°F (2017) | 41.0°F (2001) | 1.68 in (1945) |
| September 28 | 90.0°F (2019) | 37.9°F (2003) | 0.87 in (1981) |
| September 29 | 89.1°F (2021) | 37.9°F (2022) | 0.57 in (2005) |
| September 30 | 88.0°F (2019) | 37.9°F (2003) | 1.09 in (1945) |