Rosebud County, Montana
Shrink-swell clay limits houses without basements on 25% of Rosebud County's mapped land, a higher share than 76% of US counties. A shallow water table limits basements on under 1%.
38.4% 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. 54% 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 Rosebud County
| Expansive clay (limits slab homes) | 25.1% |
| High water table (limits basements) | 0.5% |
| Septic fields very limited | 73.0% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 26.1% |
| Mapped soil | 4,869,474 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Midway | 7% | n/a |
| Cabba | 5% | n/a |
| Yamacall | 5% | n/a |
| Cabbart | 5% | under 1% |
| Delpoint | 4% | n/a |
| Ringling | 4% | n/a |
How we count · survey areas MT643 (2025-09-03), MT649 (2025-09-03)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 26% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 25% of the mapped land.
Clay shrinks as it dries: 38.4% of the county is in drought on the latest map, and 25% of Rosebud County's mapped land has shrink-swell clay.
Rain over the 12 months to August 2026: 14.33 in, 0.34 in below the 1991-2020 average year of 14.67 in.
USDA rates 73% of the land very limited for septic absorption fields.
Drought
38.4% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 35 of the last 52 weeks; the most was 100% of its area, in 13 weeks, most recently on the August 11, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 59.8% |
| D1 moderate drought or worse | 38.4% |
| D2 severe or worse | 10% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
2 flood losses since 2016, $3,236 paid. The worst year was 2019, with 1.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 0 |
| 2018 | 1 |
| 2019 | 1 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 14.67 in |
| 12 months to August 2026 | 14.33 in (-0.34) |
| 2025 | 17.72 in (+3.05) |
| Wettest year since 1895 | 2019: 21.05 in |
| Driest year since 1895 | 1934: 7.47 in |
| Days with 1 inch or more, normal at FORSYTH (7 mi away) | 2.1 |
Homes
| Housing units | 3,779 |
| Median year built | 1978 |
| Built before 1980 | 54% |
| Built 2000 or later | 11% |
| Owner-occupied | 64% |
| Median value, owner-occupied | $182,400 |
| Single-family detached | 62% |
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 |
|---|---|---|---|
| Treasure County, MT | 29 mi | 44% | 4% |
| Custer County, MT | 53 mi | 19% | 1% |
| Big Horn County, MT | 67 mi | 30% | 1% |
| Prairie County, MT | 71 mi | 10% | 1% |
| Powder River County, MT | 75 mi | 30% | under 1% |
| Garfield County, MT | 77 mi | 22% | under 1% |
| Yellowstone County, MT | 79 mi | 23% | 3% |
| Musselshell County, MT | 88 mi | 24% | 1% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status