Warren County, Missouri
A shallow water table limits basements on 59% of Warren County's mapped land, a higher share than 74% of US counties. Shrink-swell clay limits houses without basements on 52%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 5 flood losses here since 2016. 23% of homes were built before 1980, against 50% nationally; the median home dates from 1998.
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 Warren County
| Expansive clay (limits slab homes) | 52.0% |
| High water table (limits basements) | 59.4% |
| Septic fields very limited | 96.7% |
| Clay swell (LEP, by area) | 6.3% |
| High-swell land (LEP 6%+) | 52.1% |
| Mapped soil | 280,019 acres |
How we count · survey areas MO219 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 6.3% by land area here, and 52% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 52% of the mapped land.
On 59% of Warren 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: 38.89 in, 3.82 in below the 1991-2020 average year of 42.71 in.
USDA rates 97% 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 14 of the last 52 weeks; the most was 100% of its area, in 6 weeks, most recently on the February 10, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
5 flood losses since 2016, $1.1 million paid. The worst year was 2017, with 3.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 3 |
| 2018 | 0 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 42.71 in |
| 12 months to August 2026 | 38.89 in (-3.82) |
| 2025 | 37.26 in (-5.45) |
| Wettest year since 1895 | 1993: 65.71 in |
| Driest year since 1895 | 1930: 25.10 in |
| Days with 1 inch or more, normal at WASHINGTON (18 mi away) | 12 |
Homes
| Housing units | 16,161 |
| Median year built | 1998 |
| Built before 1980 | 23% |
| Built 2000 or later | 47% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $260,400 |
| Single-family detached | 79% |
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 |
|---|---|---|---|
| Montgomery County, MO | 20 mi | 67% | 76% |
| Lincoln County, MO | 23 mi | 64% | 55% |
| Franklin County, MO | 25 mi | 14% | 61% |
| St. Charles County, MO | 26 mi | 41% | 62% |
| Gasconade County, MO | 29 mi | 37% | 76% |
| Calhoun County, IL | 38 mi | 4% | 25% |
| St. Louis County, MO | 39 mi | 5% | 37% |
| Pike County, MO | 40 mi | 45% | 69% |
Sources: USDA SSURGO (September 2, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status