Frost Line Depth in Macon County, Illinois
- 2 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Macon County.
Nearby official codes require 36–40 in (2 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 110 nights a year at or below 32 °F (NOAA 1991–2020, Decatur Wtp, 2.2 mi).
Checked Oct 2026. Report a correction
Does Macon County have an official frost line depth?
No adopted frost line depth found for Macon County in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 36 to 40 in. Use the deepest of them until the building department confirms Macon County’s own number.
What frost line depth does Macon County use for footings under Table R301.2(1)? Is it 36 in, like Decatur?
How deep do footings, decks and water lines need to be in Macon County?
Drawn with the deepest nearby official value (40 in). Confirm Macon County’s own depth before you dig.
House or garage footing in Macon County: dig at least 40 in (102 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 40 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 40 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 46 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 40 in | No code rule; common practice is below the frost line |
Work out posts, concrete and footing sizes with the fence post depth calculator or the deck footing calculator.
How cold does it get in Macon County?
- J
- F
- M
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Average lows are at or below freezing from Dec to Feb. 110 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 19.7 °F.
NOAA 1991–2020 climate normals, Decatur Wtp station, 2.2 mi away, elevation 639 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 19.7 | 23.5 | 32.8 | 43.3 | 53.8 | 63.1 | 66.5 | 64.9 | 57 | 45.7 | 34.3 | 25 |
| High | 34 | 39.1 | 50.8 | 63.4 | 73.5 | 82.2 | 84.7 | 83.5 | 77.7 | 65.3 | 50.3 | 38.6 |
Macon County has fewer freezing nights than 57 of the 71 other Illinois places we track. The Illinois median is 127. Coldest: Hoffman Estates; mildest: Madison County.
What frost line depth do towns near Macon County use?
2 official codes near Macon County are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Decatur | 36 in | 2 mi away |
| Bloomington | 40 in | 43 mi away |
How likely is the soil in Macon County to heave?
USDA rates the sampled soil around Macon County as 43% moderate, 57% high for frost action (main soils: Flanagan, Birkbeck, Drummer).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Macon County at a glance
- Frost line depth
- No official local value
- Population (2023 est.)
- 100,591
- Mean annual temperature
- 53 °F
- ZIP codes (27)
- 61749 · 61756 · 61818 · 61830 · 61882 · 61914 · 61925 · 61937 · 62501 · 62513 · 62514 · 62521 · 62522 · 62523 · 62526 · 62532 · 62535 · 62537 · 62539 · 62543 · 62544 · 62547 · 62549 · 62550 · 62551 · 62554 · 62573