Montgomery County, Missouri
A shallow water table limits basements on 76% of Montgomery County's mapped land, a higher share than 86% of US counties. Shrink-swell clay limits houses without basements on 67%.
11.8% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 2 flood losses here since 2016. 53% of homes were built before 1980, against 50% nationally; the median home dates from 1978.
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 Montgomery County
| Expansive clay (limits slab homes) | 67.1% |
| High water table (limits basements) | 76.1% |
| Septic fields very limited | 98.7% |
| Clay swell (LEP, by area) | 7.8% |
| High-swell land (LEP 6%+) | 68.0% |
| Mapped soil | 346,944 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Mexico | 24% | n/a |
| Keswick | 11% | n/a |
| Armster | 9% | n/a |
| Belknap | 4% | n/a |
| Gasconade | 4% | n/a |
| Putnam | 4% | n/a |
How we count · survey areas MO139 (2025-09-02)
What the numbers mean here
Clay swell averages a linear extensibility of 7.8% by land area here, and 68% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 67% of the mapped land.
Clay shrinks as it dries: 11.8% of the county is in drought on the latest map, and 67% of Montgomery County's mapped land has shrink-swell clay.
On 76% of Montgomery 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: 36.83 in, 4.97 in below the 1991-2020 average year of 41.80 in.
USDA rates 99% of the land very limited for septic absorption fields.
Drought
11.8% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 16 of the last 52 weeks; the most was 100% of its area, in 9 weeks, most recently on the March 3, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 100% |
| D1 moderate drought or worse | 11.8% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
2 flood losses since 2016, $11,636 paid. The worst year was 2024, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 0 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 41.80 in |
| 12 months to August 2026 | 36.83 in (-4.97) |
| 2025 | 35.67 in (-6.13) |
| Wettest year since 1895 | 1993: 63.51 in |
| Driest year since 1895 | 1930: 23.53 in |
| Days with 1 inch or more, normal at VANDALIA (26 mi away) | 10.7 |
Homes
| Housing units | 5,832 |
| Median year built | 1978 |
| Built before 1980 | 53% |
| Built 2000 or later | 19% |
| Owner-occupied | 73% |
| Median value, owner-occupied | $178,700 |
| Single-family detached | 80% |
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 |
|---|---|---|---|
| Warren County, MO | 20 mi | 52% | 59% |
| Callaway County, MO | 26 mi | 54% | 63% |
| Audrain County, MO | 28 mi | 90% | 98% |
| Lincoln County, MO | 28 mi | 64% | 55% |
| Pike County, MO | 32 mi | 45% | 69% |
| Gasconade County, MO | 34 mi | 37% | 76% |
| Osage County, MO | 39 mi | 29% | 70% |
| Franklin County, MO | 42 mi | 14% | 61% |
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