September weather in Knox, IN
The average temperature in Knox in September is 63.2°F (52.3°F–74.0°F). Average precipitation: 3.47 inches.
September is a fall month in Knox, and is warmer than the annual average of 49.5°F. Daily temperatures swing about 21.7°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 16m. For travel, September is one of the best months of the year to visit.
Avg High
74.0°F
Avg Low
52.3°F
Precipitation
3.47 in
Daylight
12h 16m
September records in Knox
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 90.0°F (1912) | 39.0°F (2009) | 1.52 in (2003) |
| September 2 | 93.0°F (1913) | 37.0°F (1909) | 0.92 in (2010) |
| September 3 | 93.0°F (1913) | 36.0°F (1908) | 2.55 in (1993) |
| September 4 | 88.0°F (2012) | 48.0°F (1908) | 0.85 in (2018) |
| September 5 | 88.0°F (1912) | 45.0°F (2010) | 1.86 in (2008) |
| September 6 | 89.1°F (2014) | 45.0°F (2025) | 0.79 in (1993) |
| September 7 | 88.0°F (1916) | 43.0°F (2025) | 0.65 in (1917) |
| September 8 | 89.1°F (2016) | 41.0°F (2025) | 0.96 in (2007) |
| September 9 | 88.0°F (2015) | 39.9°F (1914) | 0.75 in (2009) |
| September 10 | 90.0°F (2013) | 36.0°F (1917) | 3.60 in (2016) |
| September 11 | 96.1°F (2013) | 28.9°F (1917) | 3.60 in (1992) |
| September 12 | 95.0°F (2013) | 34.0°F (1917) | 1.30 in (2000) |
| September 13 | 87.1°F (1915) | 41.0°F (1913) | 2.00 in (2008) |
| September 14 | 89.1°F (1915) | 37.9°F (2013) | 1.17 in (1911) |
| September 15 | 89.1°F (2021) | 37.9°F (2011) | 3.80 in (2008) |
| September 16 | 89.1°F (2021) | 33.1°F (1916) | 1.50 in (2005) |
| September 17 | 88.0°F (1906) | 39.9°F (2011) | 0.95 in (1997) |
| September 18 | 91.0°F (1906) | 33.1°F (1916) | 2.02 in (1907) |
| September 19 | 87.1°F (1908) | 36.0°F (1916) | 2.55 in (2013) |
| September 20 | 88.0°F (1908) | 36.0°F (2020) | 1.08 in (1917) |
| September 21 | 90.0°F (1908) | 37.9°F (2012) | 1.29 in (2014) |
| September 22 | 91.9°F (2010) | 37.9°F (1913) | 2.68 in (2025) |
| September 23 | 89.1°F (2017) | 30.9°F (1913) | 0.93 in (2024) |
| September 24 | 91.0°F (2017) | 36.0°F (1916) | 0.90 in (2025) |
| September 25 | 89.1°F (2007) | 37.0°F (1907) | 0.70 in (1911) |
| September 26 | 86.0°F (1908) | 34.0°F (1907) | 1.24 in (1993) |
| September 27 | 88.0°F (2017) | 35.1°F (1909) | 2.00 in (1916) |
| September 28 | 86.0°F (2021) | 35.1°F (1909) | 3.65 in (2019) |
| September 29 | 82.0°F (2025) | 35.1°F (1908) | 1.02 in (2005) |
| September 30 | 82.9°F (2025) | 33.1°F (1912) | 0.55 in (1913) |