Rivers in Iowa
Winnebago River at Mason City
Below flood stage
5.70ftStage
Observed Wed, Sep 23, 3:15 AM CDT
- Flood stage
- 10.00 ft
- Record crest
- 18.74 ft2008
Flood stages and impacts
| Category | Stage |
|---|---|
| Major flood | 15.50 ft |
| Moderate flood | 14.50 ft |
| Minor flood | 10.00 ft |
| Action | 8.00 ft |
- 20.50 ftWater affects the floodwall at the water treatment plant located at 13th St NE.
- 17.40 ftWater reaches bottom of railroad bridge east of Kentucky Ave bridge.
- 15.00 ftThis is the approximate top of levee protection. Levees run from the 12th St NE bridge to 9th St along the east bank and also from 8th St to 6th St and Hampshire St.
- 14.00 ftWater may flow over the city dikes.
- 12.00 ftWidespread flooding occurs along the river. Some backwater effects are possible along Willow Creek between downtown Mason City and the confluence with the Winnebago river.
- 11.00 ftSandbagging occurs on the dike from 12th St NE to Carolina St.
- 10.00 ftWidespread flooding occurs at city parks. Water reaches the underside of the 12th St NE bridge at the piers.
- 8.00 ftWater affects east and west city parks in the 12th St NE area.
- 7.00 ftWater affects low-lying areas along the river.
Flood outlook
Chance of flooding, September to November
| Category | Chance |
|---|---|
| Minor flooding | Under 5% |
| Moderate flooding | Under 5% |
| Major flooding | Under 5% |
The three-month chances are the River Forecast Centers’ long-range flood outlook, issued August 28, 2026.
Crest history
94 crests on NOAA’s list since 1933.
| # | Date | Stage |
|---|---|---|
| 1 | June 8, 2008 | 18.74 ft |
| 2 | March 30, 1933 | 15.70 ft |
| 3 | March 27, 1961 | 14.80 ft |
| 4 | May 22, 2004 | 14.67 ft |
| 5 | April 11, 1965 | 14.27 ft |
| 6 | September 22, 2016 | 14.07 ft |
| 7 | August 31, 1962 | 13.06 ft |
| 8 | April 1, 1993 | 12.59 ft |
| 9 | April 7, 1951 | 12.44 ft |
| 10 | July 8, 1969 | 12.25 ft |
| 11 | June 12, 1944 | 12.20 ft |
| 12 | September 21, 2018 | 12.17 ft |
| 13 | June 8, 1984 | 11.94 ft |
| 14 | June 21, 1954 | 11.85 ft |
| 15 | July 21, 1999 | 11.84 ft |
| 16 | April 12, 2001 | 11.83 ft |
| 17 | May 30, 1980 | 11.66 ft |
| 18 | May 18, 1991 | 11.58 ft |
| 19 | August 23, 1979 | 11.33 ft |
| 20 | February 27, 2023 | 11.24 ft |
| 21 | February 28, 1948 | 11.22 ft |
| 22 | March 12, 2010 | 11.20 ft |
| 23 | August 19, 2025 | 11.19 ft |
| 24 | June 22, 2024 | 10.98 ft |
| 25 | April 13, 2022 | 10.91 ft |
Most recent crests
- August 19, 2025: 11.19 ft
- June 22, 2024: 10.98 ft
- February 27, 2023: 11.24 ft
- April 13, 2022: 10.91 ft
- August 28, 2021: 5.78 ft
- March 5, 2020: 7.34 ft
- October 6, 2019: 7.27 ft
- March 20, 2019: 10.42 ft
- March 17, 2019: 10.54 ft
- September 21, 2018: 12.17 ft
Nearby
Upstream, downstream and the gauges around this one.
What this means
Forecasts by the North Central River Forecast Center. Forecasts are issued as needed during times of high water, but are not routinely available.
Sources
Stage, flood stages, impacts and crest history from NOAA’s National Water Prediction Service. Streamflow and the daily record from the U.S. Geological Survey.