September weather in Riley, IN
The average temperature in Riley in September is 66.6°F (54.2°F–79.0°F). Average precipitation: 2.93 inches.
September is a fall month in Riley, and is warmer than the annual average of 53.5°F. Daily temperatures swing about 24.8°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 15m. For travel, September is one of the best months of the year to visit.
Avg High
79.0°F
Avg Low
54.2°F
Precipitation
2.93 in
Daylight
12h 15m
September records in Riley
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 97.0°F (2011) | 46.0°F (2009) | 3.12 in (2003) |
| September 2 | 98.1°F (2011) | 46.9°F (2009) | 0.93 in (2012) |
| September 3 | 98.1°F (2011) | 48.0°F (2024) | 0.64 in (2008) |
| September 4 | 96.1°F (1999) | 48.9°F (2010) | 0.56 in (2021) |
| September 5 | 95.0°F (1999) | 44.1°F (2010) | 0.43 in (2023) |
| September 6 | 95.0°F (1998) | 43.0°F (2017) | 0.28 in (2007) |
| September 7 | 93.0°F (2015) | 41.0°F (2017) | 1.55 in (2012) |
| September 8 | 93.9°F (2002) | 39.0°F (2024) | 3.13 in (2007) |
| September 9 | 93.9°F (2002) | 39.9°F (2024) | 0.42 in (2015) |
| September 10 | 97.0°F (2013) | 42.1°F (1999) | 2.35 in (2000) |
| September 11 | 95.0°F (2013) | 43.0°F (2017) | 0.50 in (2010) |
| September 12 | 91.9°F (2019) | 45.0°F (2007) | 0.88 in (2008) |
| September 13 | 91.9°F (2011) | 42.1°F (2015) | 0.07 in (2006) |
| September 14 | 91.0°F (1998) | 39.0°F (2014) | 0.60 in (2002) |
| September 15 | 91.0°F (2025) | 37.9°F (2007) | 0.74 in (2014) |
| September 16 | 90.0°F (2019) | 39.9°F (2000) | 0.41 in (2016) |
| September 17 | 91.0°F (2018) | 42.1°F (1999) | 1.05 in (2006) |
| September 18 | 93.0°F (2018) | 42.1°F (1999) | 0.88 in (2006) |
| September 19 | 93.0°F (2018) | 37.0°F (2020) | 1.10 in (2002) |
| September 20 | 93.0°F (2018) | 37.9°F (2020) | 0.82 in (2002) |
| September 21 | 95.0°F (2022) | 39.9°F (2020) | 0.48 in (2012) |
| September 22 | 93.9°F (2017) | 33.1°F (1999) | 0.91 in (2021) |
| September 23 | 93.9°F (2010) | 36.0°F (1999) | 0.30 in (2024) |
| September 24 | 93.0°F (2017) | 34.0°F (2012) | 0.60 in (2018) |
| September 25 | 91.9°F (2017) | 37.0°F (2001) | 1.64 in (2005) |
| September 26 | 91.9°F (2017) | 33.1°F (2001) | 1.43 in (2003) |
| September 27 | 91.0°F (1998) | 37.9°F (2001) | 1.00 in (2024) |
| September 28 | 91.9°F (1999) | 34.0°F (2022) | 0.57 in (2005) |
| September 29 | 91.0°F (2025) | 34.0°F (2022) | 1.05 in (1999) |
| September 30 | 91.9°F (2019) | 35.1°F (2003) | 0.30 in (2016) |