September weather in Lewistown, MT
The average temperature in Lewistown in September is 55.9°F (41.5°F–70.4°F). Average precipitation: 1.39 inches.
September is a fall month in Lewistown, and is warmer than the annual average of 43.1°F. Daily temperatures swing about 28.9°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 19m. For travel, September is a comfortable month to visit.
Avg High
70.4°F
Avg Low
41.5°F
Precipitation
1.39 in
Daylight
12h 19m
September records in Lewistown
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 97.0°F (1983) | 26.1°F (1930) | 0.90 in (1973) |
| September 2 | 96.1°F (1945) | 28.9°F (1900) | 1.25 in (1953) |
| September 3 | 97.0°F (2022) | 28.9°F (1929) | 0.85 in (1909) |
| September 4 | 93.0°F (1924) | 19.9°F (1929) | 0.80 in (1901) |
| September 5 | 97.0°F (2020) | 28.0°F (1956) | 0.97 in (1937) |
| September 6 | 93.9°F (1908) | 21.0°F (1929) | 1.06 in (1930) |
| September 7 | 100.0°F (2022) | 18.0°F (1929) | 1.45 in (1941) |
| September 8 | 95.0°F (1979) | 19.0°F (1929) | 1.37 in (1896) |
| September 9 | 99.0°F (1909) | 12.9°F (1896) | 1.13 in (1932) |
| September 10 | 91.0°F (1966) | 16.0°F (1896) | 1.00 in (1903) |
| September 11 | 98.1°F (1908) | 10.9°F (1921) | 1.43 in (1978) |
| September 12 | 91.0°F (1953) | 21.9°F (1921) | 1.33 in (1978) |
| September 13 | 90.0°F (1959) | 23.0°F (1896) | 1.23 in (1967) |
| September 14 | 93.9°F (1948) | 19.0°F (1970) | 0.85 in (1906) |
| September 15 | 93.0°F (1908) | 23.0°F (1916) | 0.97 in (2017) |
| September 16 | 91.0°F (1998) | 21.9°F (1912) | 0.97 in (1947) |
| September 17 | 91.0°F (2009) | 23.0°F (1902) | 0.93 in (1946) |
| September 18 | 90.0°F (1966) | 19.0°F (1965) | 4.35 in (2024) |
| September 19 | 91.9°F (1938) | 21.9°F (1943) | 0.60 in (1941) |
| September 20 | 91.9°F (1922) | 18.0°F (1983) | 1.00 in (1919) |
| September 21 | 91.9°F (1938) | 19.0°F (1995) | 1.76 in (1959) |
| September 22 | 95.0°F (1905) | 23.0°F (2000) | 1.02 in (2023) |
| September 23 | 90.0°F (1966) | 18.0°F (1926) | 0.65 in (1913) |
| September 24 | 89.1°F (1922) | 6.1°F (1926) | 0.70 in (1903) |
| September 25 | 91.9°F (1922) | 12.9°F (1926) | 0.62 in (1924) |
| September 26 | 90.0°F (2015) | 9.0°F (1900) | 0.53 in (1946) |
| September 27 | 88.0°F (1963) | 17.1°F (1900) | 0.98 in (2014) |
| September 28 | 87.1°F (1909) | 17.1°F (1984) | 0.36 in (1954) |
| September 29 | 89.1°F (1967) | 19.2°F (2019) | 1.00 in (1905) |
| September 30 | 93.0°F (1906) | 17.1°F (1985) | 1.14 in (2022) |