Waterloo Weather in September
Average highs run from 82°F on September 1 to 73°F on September 30, and lows from 61°F to 50°F. Normal precipitation for the month is 3.02 in over about 8 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
- 78°F
- Average low
- 56°F
- Precipitation
- 3.02 in
- Record high
- 100°FSep 21, 2022
- Record low
- 37°FSep 13, 2014
- Chance of a freeze
- 5%
- Days of 90°F or more
- 2.7
- Daylight
- 13 h 06 min to 11 h 47 min
- Cloud cover
- 46%
- Humidity
- 66%
- Dew point
- 52°F
- Wind
- 10.5 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 | 82°F | 61°F | 94°F 2012 | 46°F 2009 | 28% | 0% |
| Sep 2 | 82°F | 61°F | 94°F 2011 | 48°F 2009 | 28% | 0% |
| Sep 3 | 82°F | 61°F | 96°F 2026 | 45°F 2006 | 28% | 0% |
| Sep 4 | 81°F | 60°F | 95°F 2023 | 46°F 2006 | 28% | 0% |
| Sep 5 | 81°F | 60°F | 97°F 2012 | 48°F 2010 | 28% | 0% |
| Sep 6 | 81°F | 60°F | 92°F 2026 | 45°F 2008 | 28% | 0% |
| Sep 7 | 81°F | 59°F | 94°F 2015 | 45°F 2008 | 28% | 0% |
| Sep 8 | 81°F | 59°F | 88°F 2013 | 48°F 2012 | 28% | 0% |
| Sep 9 | 80°F | 59°F | 98°F 2026 | 42°F 2008 | 28% | 0% |
| Sep 10 | 80°F | 58°F | 96°F 2013 | 42°F 2008 | 28% | 0% |
| Sep 11 | 80°F | 58°F | 94°F 2013 | 47°F 2022 | 28% | 0% |
| Sep 12 | 80°F | 58°F | 93°F 2012 | 46°F 2007 | 27% | 0% |
| Sep 13 | 79°F | 57°F | 90°F 2005 | 37°F 2014 | 27% | 0% |
| Sep 14 | 79°F | 57°F | 95°F 2025 | 37°F 2014 | 27% | 0% |
| Sep 15 | 79°F | 56°F | 92°F 2017 | 39°F 2007 | 27% | 0% |
| Sep 16 | 78°F | 56°F | 91°F 2017 | 39°F 2011 | 27% | |
| Sep 17 | 78°F | 56°F | 91°F 2006 | 41°F 2014 | 27% | |
| Sep 18 | 78°F | 55°F | 92°F 2018 | 42°F 2012 | 27% | |
| Sep 19 | 77°F | 55°F | 89°F 2013 | 42°F 2012 | 27% | |
| Sep 20 | 77°F | 54°F | 92°F 2022 | 42°F 2006 | 28% | |
| Sep 21 | 77°F | 54°F | 100°F 2022 | 41°F 2006 | 28% | |
| Sep 22 | 76°F | 54°F | 98°F 2005 | 43°F 2018 | 28% | |
| Sep 23 | 76°F | 53°F | 94°F 2017 | 39°F 2012 | 27% | |
| Sep 24 | 76°F | 53°F | 90°F 2016 | 39°F 2011 | 27% | |
| Sep 25 | 75°F | 52°F | 89°F 2005 | 42°F 2011 | 27% | |
| Sep 26 | 75°F | 52°F | 82°F 2008 | 41°F 2011 | 27% | |
| Sep 27 | 74°F | 51°F | 87°F 2021 | 43°F 2011 | 27% | |
| Sep 28 | 74°F | 51°F | 89°F 2021 | 42°F 2006 | 27% | |
| Sep 29 | 73°F | 51°F | 91°F 2021 | 37°F 2005 | 27% | |
| Sep 30 | 73°F | 50°F | 94°F 2023 | 37°F 2005 | 27% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- September 1
- sunrise 6:52 AM, sunset 7:58 PM
- September 30
- sunrise 7:21 AM, sunset 7:08 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00258795 (Valley NWS), public domain. Records: NOAA GHCN-Daily, station USC00253467, 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.