Coles County, Illinois
A shallow water table limits basements on 85% of Coles County's mapped land, a higher share than 92% of US counties. Shrink-swell clay limits houses without basements on 19%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 17 flood losses here since 2016. 65% of homes were built before 1980, against 50% nationally; the median home dates from 1971.
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 Coles County
| Expansive clay (limits slab homes) | 18.6% |
| High water table (limits basements) | 84.6% |
| Septic fields very limited | 96.9% |
| Clay swell (LEP, by area) | 4.5% |
| High-swell land (LEP 6%+) | 13.3% |
| Mapped soil | 326,445 acres |
How we count · survey areas IL029 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.5% by land area here, and 13% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 19% of the mapped land.
On 85% of Coles 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: 43.15 in, 1.76 in above the 1991-2020 average year of 41.39 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 22 of the last 52 weeks; the most was 100% of its area, in 21 weeks, most recently on the March 10, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 26.9% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
17 flood losses since 2016, $300,916 paid. The worst year was 2018, with 9.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 2 |
| 2018 | 9 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 6 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 41.39 in |
| 12 months to August 2026 | 43.15 in (+1.76) |
| 2025 | 31.21 in (-10.18) |
| Wettest year since 1895 | 1927: 53.99 in |
| Driest year since 1895 | 1914: 25.59 in |
| Days with 1 inch or more, normal at CHARLESTON (4 mi away) | 11.4 |
Homes
| Housing units | 22,681 |
| Median year built | 1971 |
| Built before 1980 | 65% |
| Built 2000 or later | 13% |
| Owner-occupied | 60% |
| Median value, owner-occupied | $127,400 |
| Single-family detached | 68% |
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 |
|---|---|---|---|
| Cumberland County, IL | 17 mi | 39% | 84% |
| Douglas County, IL | 17 mi | 72% | 96% |
| Moultrie County, IL | 23 mi | 68% | 89% |
| Clark County, IL | 26 mi | 29% | 77% |
| Edgar County, IL | 28 mi | 16% | 83% |
| Shelby County, IL | 32 mi | 38% | 82% |
| Jasper County, IL | 35 mi | 51% | 89% |
| Effingham County, IL | 38 mi | 43% | 87% |
Sources: USDA SSURGO (August 31, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status