September weather in Waukesha, WI
The average temperature in Waukesha in September is 62.0°F (51.1°F–72.9°F). Average precipitation: 3.27 inches.
September is a fall month in Waukesha, and is warmer than the annual average of 46.6°F. Daily temperatures swing about 21.8°F between overnight low and afternoon high. Expect about 9 days with precipitation. Daylight averages about 12h 17m. For travel, September is one of the best months of the year to visit.
Avg High
72.9°F
Avg Low
51.1°F
Precipitation
3.27 in
Daylight
12h 17m
September records in Waukesha
| Date | Record High | Record Low | Record Precip |
|---|---|---|---|
| September 1 | 100.9°F (1953) | 39.9°F (1949) | 1.73 in (1914) |
| September 2 | 100.9°F (1953) | 42.1°F (2009) | 1.18 in (1914) |
| September 3 | 93.9°F (1953) | 41.0°F (1934) | 2.08 in (1921) |
| September 4 | 96.1°F (1925) | 34.0°F (1987) | 1.55 in (1973) |
| September 5 | 93.0°F (1912) | 42.1°F (1950) | 1.56 in (1917) |
| September 6 | 93.9°F (1922) | 37.9°F (1924) | 2.10 in (1925) |
| September 7 | 100.0°F (1922) | 37.9°F (1956) | 2.85 in (1916) |
| September 8 | 97.0°F (1978) | 39.0°F (2025) | 3.35 in (1941) |
| September 9 | 97.0°F (1955) | 39.0°F (1914) | 2.10 in (1922) |
| September 10 | 98.1°F (1931) | 28.9°F (1987) | 2.06 in (1986) |
| September 11 | 97.0°F (1931) | 35.1°F (1917) | 2.80 in (1933) |
| September 12 | 93.0°F (1952) | 35.1°F (1955) | 5.61 in (2022) |
| September 13 | 96.1°F (1939) | 37.0°F (1953) | 3.70 in (1961) |
| September 14 | 98.1°F (1939) | 34.0°F (1923) | 2.68 in (1914) |
| September 15 | 99.0°F (1939) | 34.0°F (2007) | 1.62 in (1912) |
| September 16 | 91.9°F (1994) | 30.0°F (1916) | 1.95 in (1915) |
| September 17 | 91.9°F (1931) | 35.1°F (1916) | 1.40 in (1978) |
| September 18 | 91.0°F (1935) | 33.1°F (1916) | 3.21 in (1972) |
| September 19 | 91.9°F (1947) | 33.1°F (1918) | 1.30 in (1931) |
| September 20 | 90.0°F (1895) | 30.0°F (1956) | 1.45 in (1923) |
| September 21 | 90.0°F (1895) | 28.0°F (1901) | 2.28 in (1947) |
| September 22 | 91.9°F (1895) | 30.9°F (1974) | 2.00 in (2024) |
| September 23 | 97.0°F (2009) | 27.0°F (1913) | 1.53 in (2025) |
| September 24 | 89.1°F (1935) | 30.0°F (1950) | 2.58 in (1958) |
| September 25 | 90.0°F (1920) | 26.1°F (1942) | 1.30 in (1931) |
| September 26 | 89.1°F (1920) | 27.0°F (1926) | 2.25 in (1959) |
| September 27 | 89.1°F (1998) | 30.0°F (1937) | 2.33 in (2023) |
| September 28 | 89.1°F (1952) | 25.0°F (1942) | 1.95 in (1999) |
| September 29 | 93.9°F (1953) | 28.0°F (1942) | 1.60 in (1986) |
| September 30 | 89.1°F (1952) | 28.0°F (1899) | 2.16 in (1893) |