Mason City Weather in September
Average highs run from 77°F on September 1 to 68°F on September 30, and lows from 55°F to 44°F. Normal precipitation for the month is 3.24 in over about 9 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
- 74°F
- Average low
- 50°F
- Precipitation
- 3.24 in
- Record high
- 99°FSep 9, 2013
- Record low
- 24°FSep 29, 1949
- Chance of a freeze
- 25%
- Days of 90°F or more
- 0.8
- Daylight
- 13 h 10 min to 11 h 47 min
- Cloud cover
- 51%
- Humidity
- 73%
- Dew point
- 52°F
- Wind
- 9.8 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 | 55°F | 96°F 1984 | 35°F 1949 | 29% | 0% |
| Sep 2 | 77°F | 55°F | 96°F 2023 | 36°F 1967 | 29% | 0% |
| Sep 3 | 77°F | 55°F | 98°F 2023 | 34°F 1974 | 29% | 0% |
| Sep 4 | 77°F | 54°F | 96°F 2012 | 38°F 1974 | 29% | 0% |
| Sep 5 | 77°F | 54°F | 93°F 1979 | 37°F 1962 | 29% | 0% |
| Sep 6 | 76°F | 54°F | 94°F 1985 | 37°F 2011 | 29% | 0% |
| Sep 7 | 76°F | 53°F | 97°F 1978 | 38°F 1986 | 29% | 0% |
| Sep 8 | 76°F | 53°F | 94°F 1978 | 37°F 1995 | 29% | 0% |
| Sep 9 | 76°F | 53°F | 99°F 2013 | 36°F 2008 | 29% | 0% |
| Sep 10 | 75°F | 52°F | 91°F 1978 | 36°F 1967 | 29% | 0% |
| Sep 11 | 75°F | 52°F | 95°F 2000 | 35°F 1955 | 29% | 0% |
| Sep 12 | 75°F | 52°F | 95°F 1998 | 34°F 2007 | 29% | 0% |
| Sep 13 | 75°F | 51°F | 93°F 2025 | 31°F 2014 | 29% | |
| Sep 14 | 74°F | 51°F | 93°F 1994 | 33°F 2007 | 29% | |
| Sep 15 | 74°F | 51°F | 93°F 1955 | 26°F 2011 | 29% | |
| Sep 16 | 74°F | 50°F | 92°F 1948 | 33°F 1976 | 29% | |
| Sep 17 | 73°F | 50°F | 92°F 1955 | 36°F 1971 | 29% | |
| Sep 18 | 73°F | 49°F | 90°F 1948 | 35°F 2020 | 29% | |
| Sep 19 | 73°F | 49°F | 95°F 1948 | 31°F 1991 | 29% | |
| Sep 20 | 72°F | 48°F | 92°F 2022 | 29°F 1991 | 29% | |
| Sep 21 | 72°F | 48°F | 93°F 2024 | 29°F 1999 | 29% | |
| Sep 22 | 72°F | 48°F | 92°F 2017 | 26°F 1974 | 29% | |
| Sep 23 | 71°F | 47°F | 90°F 2017 | 28°F 2012 | 29% | |
| Sep 24 | 71°F | 47°F | 90°F 2017 | 30°F 1989 | 29% | |
| Sep 25 | 70°F | 46°F | 87°F 1956 | 28°F 1951 | 29% | |
| Sep 26 | 70°F | 46°F | 89°F 1998 | 25°F 1984 | 29% | |
| Sep 27 | 70°F | 46°F | 86°F 1963 | 30°F 1961 | 29% | |
| Sep 28 | 69°F | 45°F | 88°F 2024 | 26°F 1961 | 29% | |
| Sep 29 | 69°F | 45°F | 88°F 2023 | 24°F 1949 | 29% | |
| Sep 30 | 68°F | 44°F | 92°F 2023 | 27°F 2003 | 29% |
Chance of rain
- Chance of a wet day
- Chance of snowfall
Sunrise and sunset
Times for 2026, local time (CDT).
- September 1
- sunrise 6:37 AM, sunset 7:47 PM
- September 30
- sunrise 7:09 AM, sunset 6:56 PM
Other months
Sources
Normals: NOAA NCEI U.S. Climate Normals, 1991-2020, station USC00135230 (Mason City), public domain. Records: NOAA GHCN-Daily, station USW00014940, 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.