Waterloo Weather in September
Average highs run from 77°F on September 1 to 68°F on September 30, and lows from 56°F to 44°F. Normal precipitation for the month is 3.88 in over about 10 wet days.
September day by day
The normal high and low for each date, and the record, in °F.
- Normal low
- Normal high
- Record high
- Record low
September at a glance
- Average high
- 73°F
- Average low
- 50°F
- Precipitation
- 3.88 in
- Record high
- 100°FSep 7, 1939
- Record low
- 20°FSep 26, 1893
- Chance of a freeze
- 16%
- Days of 90°F or more
- 1.2
- Daylight
- 13 h 11 min to 11 h 47 min
- Cloud cover
- 53%
- Humidity
- 74%
- Dew point
- 53°F
- Wind
- 9.4 mph
Every day of the month
A wet day has at least 0.01 inch of precipitation; snow means at least 0.1 inch of snowfall.
| Date | Normal high | Normal low | Record high | Record low | Chance wet | Chance of snow |
|---|---|---|---|---|---|---|
| Sep 1 | 77°F | 56°F | 99°F 1953 | 36°F 1909 | 34% | 0% |
| Sep 2 | 77°F | 56°F | 98°F 1953 | 30°F 1893 | 34% | 0% |
| Sep 3 | 77°F | 55°F | 95°F 1937 | 34°F 1893 | 34% | 0% |
| Sep 4 | 76°F | 55°F | 95°F 1925 | 36°F 1893 | 34% | 0% |
| Sep 5 | 76°F | 55°F | 93°F 1922 | 37°F 1893 | 34% | 0% |
| Sep 6 | 76°F | 54°F | 98°F 1922 | 36°F 1962 | 34% | 0% |
| Sep 7 | 76°F | 54°F | 100°F 1939 | 37°F 1956 | 34% | 0% |
| Sep 8 | 75°F | 53°F | 98°F 1922 | 39°F 1957 | 34% | 0% |
| Sep 9 | 75°F | 53°F | 96°F 1955 | 38°F 1918 | 34% | 0% |
| Sep 10 | 75°F | 53°F | 95°F 1931 | 33°F 1917 | 34% | 0% |
| Sep 11 | 74°F | 52°F | 94°F 1931 | 32°F 1917 | 34% | 0% |
| Sep 12 | 74°F | 52°F | 92°F 1939 | 33°F 1902 | 34% | 0% |
| Sep 13 | 74°F | 51°F | 97°F 1939 | 33°F 1902 | 34% | 0% |
| Sep 14 | 73°F | 51°F | 100°F 1939 | 31°F 1923 | 34% | 0% |
| Sep 15 | 73°F | 51°F | 100°F 1939 | 33°F 1904 | 34% | 0% |
| Sep 16 | 73°F | 50°F | 92°F 1948 | 31°F 1916 | 33% | 0% |
| Sep 17 | 72°F | 50°F | 90°F 1927 | 29°F 1893 | 33% | 0% |
| Sep 18 | 72°F | 49°F | 92°F 1955 | 31°F 1903 | 33% | 0% |
| Sep 19 | 72°F | 49°F | 93°F 1948 | 30°F 1901 | 33% | 0% |
| Sep 20 | 71°F | 48°F | 91°F 1895 | 29°F 1956 | 33% | 0% |
| Sep 21 | 71°F | 48°F | 90°F 1895 | 33°F 1897 | 33% | 0% |
| Sep 22 | 71°F | 48°F | 93°F 1937 | 28°F 1974 | 33% | 0% |
| Sep 23 | 70°F | 47°F | 94°F 1937 | 29°F 1974 | 33% | 0% |
| Sep 24 | 70°F | 47°F | 92°F 2017 | 24°F 1893 | 33% | 0% |
| Sep 25 | 69°F | 46°F | 91°F 1920 | 23°F 1893 | 33% | 0% |
| Sep 26 | 69°F | 46°F | 90°F 2017 | 20°F 1893 | 33% | 0% |
| Sep 27 | 69°F | 45°F | 88°F 1998 | 20°F 1893 | 33% | 0% |
| Sep 28 | 68°F | 45°F | 88°F 1952 | 20°F 1893 | 34% | 0% |
| Sep 29 | 68°F | 45°F | 92°F 1953 | 22°F 1893 | 34% | 0% |
| Sep 30 | 68°F | 44°F | 89°F 1971 | 20°F 1899 | 34% | 0% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- September 1
- sunrise 6:20 AM, sunset 7:31 PM
- September 30
- sunrise 6:52 AM, sunset 6:39 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00478910 (Waterloo Wwtp), public domain. Records: NOAA GHCN-Daily, station USC00478919, every year on file, quality-flagged values removed. Cloud, humidity, wind and sunshine: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.