September weather in Castle Rock, CO
The average temperature in Castle Rock in September is 61.7°F (46.6°F–76.7°F). Average precipitation: 1.39 inches. Average snowfall is 0.4 inches.
September is a fall month in Castle Rock, and is warmer than the annual average of 49.5°F. Daily temperatures swing about 30.1°F between overnight low and afternoon high. Expect about 6 days with precipitation. Daylight averages about 12h 15m. For travel, September is a comfortable month to visit.
Avg High
76.7°F
Avg Low
46.6°F
Precipitation
1.39 in
Snow
0.4 in
September records in Castle Rock
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 97.0°F (2021) | 37.9°F (1895) | 1.22 in (2000) |
| September 2 | 96.1°F (2019) | 34.0°F (1974) | 0.53 in (1997) |
| September 3 | 98.1°F (2019) | 30.9°F (1973) | 0.75 in (2011) |
| September 4 | 93.0°F (1899) | 35.1°F (1968) | 0.70 in (1909) |
| September 5 | 96.1°F (2020) | 36.0°F (1910) | 0.68 in (2004) |
| September 6 | 99.0°F (2020) | 35.1°F (1898) | 1.01 in (1963) |
| September 7 | 96.1°F (1903) | 34.0°F (1898) | 1.05 in (1894) |
| September 8 | 96.1°F (1902) | 32.0°F (2001) | 0.77 in (1989) |
| September 9 | 95.0°F (2022) | 28.9°F (2001) | 0.68 in (1980) |
| September 10 | 96.1°F (2021) | 28.9°F (1907) | 0.95 in (2014) |
| September 11 | 99.0°F (2021) | 28.0°F (1898) | 0.78 in (1987) |
| September 12 | 100.9°F (2021) | 26.1°F (1902) | 0.84 in (2013) |
| September 13 | 91.9°F (1911) | 28.9°F (1974) | 0.98 in (2002) |
| September 14 | 91.0°F (2018) | 25.0°F (1914) | 1.25 in (1912) |
| September 15 | 91.0°F (1978) | 21.0°F (1993) | 2.80 in (2013) |
| September 16 | 93.9°F (2021) | 26.1°F (1903) | 0.60 in (1896) |
| September 17 | 96.1°F (2021) | 23.0°F (1965) | 0.70 in (1896) |
| September 18 | 91.0°F (2000) | 21.9°F (1965) | 1.00 in (1965) |
| September 19 | 97.0°F (2021) | 15.1°F (1971) | 0.66 in (2002) |
| September 20 | 91.9°F (2010) | 19.9°F (1912) | 0.70 in (1965) |
| September 21 | 90.0°F (1980) | 21.9°F (1895) | 1.55 in (1902) |
| September 22 | 89.1°F (1905) | 23.0°F (1994) | 1.12 in (1902) |
| September 23 | 87.1°F (2020) | 27.0°F (1975) | 1.07 in (2013) |
| September 24 | 90.0°F (1902) | 23.0°F (1926) | 0.75 in (2017) |
| September 25 | 91.0°F (2020) | 17.1°F (1926) | 1.20 in (1915) |
| September 26 | 93.0°F (2020) | 19.9°F (1984) | 0.88 in (1906) |
| September 27 | 91.0°F (2020) | 12.9°F (1908) | 0.42 in (1996) |
| September 28 | 91.0°F (2021) | 10.9°F (1984) | 0.56 in (1973) |
| September 29 | 87.1°F (1981) | 23.0°F (1999) | 1.28 in (1973) |
| September 30 | 87.1°F (1897) | 19.9°F (1896) | 1.35 in (2014) |