Audubon County, Iowa
Shrink-swell clay limits houses without basements on 30% of Audubon County's mapped land, a higher share than 80% of US counties. A shallow water table limits basements on 29%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list no flood losses here since 2016. 84% of homes were built before 1980, against 50% nationally; the median home dates from 1950.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Audubon County
| Expansive clay (limits slab homes) | 30.1% |
| High water table (limits basements) | 28.8% |
| Septic fields very limited | 98.7% |
| Clay swell (LEP, by area) | 5.1% |
| High-swell land (LEP 6%+) | 11.1% |
| Mapped soil | 284,400 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Marshall | 36% | 14% |
| Exira | 12% | n/a |
| Shelby | 10% | n/a |
| Judson | 9% | n/a |
| Colo | 8% | n/a |
| Ackmore | 6% | n/a |
How we count · survey areas IA009 (2025-09-05)
What the numbers mean here
Clay swell averages a linear extensibility of 5.1% by land area here, and 11% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 30% of the mapped land.
On 29% of Audubon County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 28.38 in, 7.05 in below the 1991-2020 average year of 35.43 in.
USDA rates 99% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 7 of the last 52 weeks; the most was 100% of its area, in 4 weeks, most recently on the August 4, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
FEMA's flood data list no flood losses in Audubon County since 2016.
Rain
| Average year, 1991-2020 | 35.43 in |
| 12 months to August 2026 | 28.38 in (-7.05) |
| 2025 | 33.38 in (-2.05) |
| Wettest year since 1895 | 2015: 51.22 in |
| Driest year since 1895 | 1930: 20.40 in |
| Days with 1 inch or more, normal at AUDUBON (2 mi away) | 9 |
Homes
| Housing units | 2,790 |
| Median year built | 1950 |
| Built before 1980 | 84% |
| Built 2000 or later | 7% |
| Owner-occupied | 76% |
| Median value, owner-occupied | $121,900 |
| Single-family detached | 92% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Guthrie County, IA | 21 mi | 62% | 66% |
| Shelby County, IA | 21 mi | 21% | 21% |
| Cass County, IA | 24 mi | 49% | 46% |
| Carroll County, IA | 25 mi | 18% | 41% |
| Adair County, IA | 33 mi | 91% | 80% |
| Crawford County, IA | 35 mi | 12% | 15% |
| Greene County, IA | 37 mi | 11% | 71% |
| Pottawattamie County, IA | 41 mi | 14% | 25% |
Sources: USDA SSURGO (September 5, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status