September weather in Casper, WY
The average temperature in Casper in September is 59.9°F (43.8°F–76.0°F). Average precipitation: 1.05 inches.
September is a fall month in Casper, and is warmer than the annual average of 47.4°F. Daily temperatures swing about 32.2°F between overnight low and afternoon high. Expect about 6 days with precipitation. Daylight averages about 12h 16m. For travel, September is a comfortable month to visit.
Avg High
76.0°F
Avg Low
43.8°F
Precipitation
1.05 in
Daylight
12h 16m
September records in Casper
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 93.0°F (2007) | 41.0°F (2005) | 0.12 in (2017) |
| September 2 | 93.9°F (2022) | 39.9°F (2006) | 0.27 in (2014) |
| September 3 | 95.0°F (2019) | 26.1°F (2014) | 0.02 in (2013) |
| September 4 | 95.0°F (2019) | 37.0°F (2008) | 0.23 in (2004) |
| September 5 | 97.0°F (2022) | 39.0°F (2008) | 0.62 in (2004) |
| September 6 | 95.0°F (2020) | 36.0°F (2025) | 0.10 in (2010) |
| September 7 | 96.1°F (2022) | 32.0°F (2020) | 0.01 in (2010) |
| September 8 | 96.1°F (2022) | 30.0°F (2014) | 0.90 in (2020) |
| September 9 | 91.9°F (2013) | 28.9°F (2020) | 0.20 in (2014) |
| September 10 | 91.9°F (2007) | 28.9°F (2020) | 0.43 in (2003) |
| September 11 | 93.0°F (2021) | 28.0°F (2014) | 0.52 in (2008) |
| September 12 | 88.0°F (2004) | 16.0°F (2014) | 0.32 in (2014) |
| September 13 | 90.0°F (2017) | 14.0°F (2014) | 0.29 in (2003) |
| September 14 | 88.0°F (2006) | 36.0°F (2003) | 0.08 in (2023) |
| September 15 | 88.0°F (2018) | 14.0°F (2014) | 0.47 in (2001) |
| September 16 | 91.0°F (2018) | 37.0°F (2005) | 0.24 in (2022) |
| September 17 | 88.0°F (2018) | 30.0°F (2014) | 1.17 in (2025) |
| September 18 | 87.1°F (2018) | 33.1°F (2014) | 0.90 in (2002) |
| September 19 | 89.1°F (2014) | 28.0°F (2014) | 0.19 in (2002) |
| September 20 | 87.1°F (2019) | 30.0°F (2010) | 0.35 in (2021) |
| September 21 | 87.1°F (2016) | 5.0°F (2017) | 1.17 in (2009) |
| September 22 | 82.9°F (2015) | 30.9°F (2002) | 0.13 in (2006) |
| September 23 | 87.1°F (2007) | 30.9°F (2002) | 0.48 in (2006) |
| September 24 | 84.9°F (2011) | 36.0°F (2002) | 0.40 in (2009) |
| September 25 | 86.0°F (2020) | 34.0°F (2017) | 0.86 in (2017) |
| September 26 | 89.1°F (2014) | 30.9°F (2018) | 0.34 in (2016) |
| September 27 | 89.1°F (2010) | 30.9°F (2018) | 0.96 in (2013) |
| September 28 | 87.1°F (2001) | 30.9°F (2020) | 0.12 in (2012) |
| September 29 | 90.0°F (2010) | 33.1°F (2009) | 0.37 in (2014) |
| September 30 | 89.1°F (2024) | 33.1°F (2013) | 0.70 in (2019) |