September weather in Sidney, MT
The average temperature in Sidney in September is 60.6°F (45.5°F–75.8°F). Average precipitation: 1.62 inches.
September is a fall month in Sidney, and is warmer than the annual average of 45.2°F. Daily temperatures swing about 30.3°F between overnight low and afternoon high. Expect about 7 days with precipitation. Daylight averages about 12h 20m. For travel, September is a comfortable month to visit.
Avg High
75.8°F
Avg Low
45.5°F
Precipitation
1.62 in
Daylight
12h 20m
September records in Sidney
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.0°F (1983) | 30.9°F (1974) | 0.81 in (1973) |
| September 2 | 100.9°F (2023) | 28.9°F (1974) | 0.83 in (1961) |
| September 3 | 100.0°F (2023) | 32.0°F (1912) | 1.79 in (1973) |
| September 4 | 99.0°F (1978) | 28.0°F (1956) | 0.63 in (1911) |
| September 5 | 99.0°F (1998) | 27.0°F (1965) | 2.52 in (1971) |
| September 6 | 100.0°F (1976) | 27.0°F (1956) | 1.53 in (1911) |
| September 7 | 96.1°F (1980) | 32.0°F (1965) | 0.84 in (1914) |
| September 8 | 99.0°F (2022) | 27.0°F (2020) | 2.92 in (1991) |
| September 9 | 100.9°F (1994) | 32.0°F (2020) | 0.95 in (1970) |
| September 10 | 97.0°F (2024) | 28.0°F (1962) | 1.35 in (2010) |
| September 11 | 93.0°F (2025) | 26.1°F (1955) | 1.07 in (1978) |
| September 12 | 95.0°F (1990) | 25.0°F (1989) | 1.33 in (2019) |
| September 13 | 91.9°F (1990) | 19.0°F (1949) | 0.40 in (1915) |
| September 14 | 90.0°F (1955) | 21.9°F (1949) | 0.51 in (2001) |
| September 15 | 93.0°F (1998) | 28.9°F (1949) | 1.93 in (1991) |
| September 16 | 96.1°F (1998) | 30.9°F (1958) | 0.52 in (1950) |
| September 17 | 95.0°F (2024) | 25.0°F (1965) | 0.31 in (2006) |
| September 18 | 93.9°F (2021) | 28.9°F (1965) | 2.64 in (2019) |
| September 19 | 93.9°F (2009) | 26.1°F (1957) | 0.89 in (1986) |
| September 20 | 93.9°F (2009) | 28.0°F (1965) | 0.96 in (2018) |
| September 21 | 88.0°F (2025) | 19.0°F (1995) | 0.52 in (1991) |
| September 22 | 88.0°F (1917) | 21.0°F (1995) | 0.95 in (2006) |
| September 23 | 93.0°F (1992) | 27.0°F (1951) | 0.85 in (2019) |
| September 24 | 93.0°F (1917) | 21.9°F (1985) | 0.42 in (1915) |
| September 25 | 95.0°F (2014) | 23.0°F (1912) | 1.00 in (1986) |
| September 26 | 96.1°F (2024) | 19.0°F (1965) | 0.62 in (1959) |
| September 27 | 93.0°F (2024) | 21.9°F (1976) | 1.27 in (1982) |
| September 28 | 97.0°F (2021) | 25.0°F (1951) | 0.61 in (1987) |
| September 29 | 98.1°F (2024) | 21.9°F (1920) | 0.30 in (1966) |
| September 30 | 98.1°F (2024) | 15.1°F (1961) | 0.45 in (1950) |