September weather in South Jacksonville, IL
The average temperature in South Jacksonville in September is 67.3°F (54.7°F–79.9°F). Average precipitation: 3.78 inches.
September is a fall month in South Jacksonville, and is warmer than the annual average of 52.8°F. Daily temperatures swing about 25.2°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 12h 15m. For travel, September is one of the best months of the year to visit.
Avg High
79.9°F
Avg Low
54.7°F
Precipitation
3.78 in
Daylight
12h 15m
September records in South Jacksonville
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 99.0°F (2011) | 48.0°F (2009) | 4.54 in (2012) |
| September 2 | 102.0°F (2011) | 46.0°F (2017) | 0.55 in (2020) |
| September 3 | 100.9°F (2011) | 46.0°F (2017) | 0.46 in (2010) |
| September 4 | 99.0°F (2011) | 48.9°F (2025) | 0.38 in (2008) |
| September 5 | 98.1°F (2007) | 51.1°F (2020) | 1.70 in (2008) |
| September 6 | 95.0°F (2015) | 46.9°F (2011) | 0.95 in (2009) |
| September 7 | 93.9°F (2015) | 42.1°F (2025) | 1.18 in (2009) |
| September 8 | 93.0°F (2013) | 42.1°F (2024) | 2.42 in (2018) |
| September 9 | 88.0°F (2006) | 42.1°F (2024) | 0.98 in (2013) |
| September 10 | 93.9°F (2013) | 45.0°F (2024) | 2.54 in (2014) |
| September 11 | 95.0°F (2013) | 48.9°F (2017) | 1.92 in (2014) |
| September 12 | 93.9°F (2013) | 45.0°F (2007) | 1.82 in (1949) |
| September 13 | 91.9°F (2019) | 39.0°F (2014) | 0.39 in (2008) |
| September 14 | 96.1°F (2025) | 39.0°F (2014) | 2.18 in (2008) |
| September 15 | 98.1°F (2025) | 39.0°F (2007) | 0.95 in (2008) |
| September 16 | 93.0°F (2025) | 39.9°F (2007) | 1.94 in (2014) |
| September 17 | 93.0°F (2018) | 46.9°F (2014) | 0.75 in (2023) |
| September 18 | 93.0°F (2018) | 46.0°F (2012) | 0.44 in (2022) |
| September 19 | 93.9°F (2018) | 41.0°F (2020) | 1.44 in (2022) |
| September 20 | 93.0°F (2018) | 39.9°F (2006) | 0.68 in (2005) |
| September 21 | 96.1°F (2017) | 39.9°F (2006) | 4.73 in (2009) |
| September 22 | 93.0°F (2007) | 46.0°F (2020) | 0.90 in (2025) |
| September 23 | 96.1°F (2017) | 37.9°F (2012) | 0.43 in (2023) |
| September 24 | 95.0°F (2007) | 37.9°F (2012) | 1.61 in (2024) |
| September 25 | 93.9°F (2017) | 39.0°F (2012) | 0.84 in (2012) |
| September 26 | 91.9°F (2017) | 41.0°F (2011) | 0.35 in (2005) |
| September 27 | 91.0°F (2017) | 43.0°F (2018) | 0.65 in (2023) |
| September 28 | 90.0°F (2019) | 39.0°F (2022) | 0.63 in (2020) |
| September 29 | 91.0°F (2021) | 39.9°F (2022) | 1.26 in (2019) |
| September 30 | 90.0°F (2025) | 42.1°F (2006) | 0.38 in (2008) |