Frost Line Depth in Mount Prospect, Illinois
- 5 verified codes nearby
- Checked Oct 2026
No official local value
No official frost line depth is published for Mount Prospect.
Nearby official codes require 42 in (5 verified codes).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 122 nights a year at or below 32 °F (NOAA 1991–2020, Chicago Palwaukee Airport, 4.3 mi).
Checked Oct 2026. Report a correction
Does Mount Prospect have an official frost line depth?
No adopted frost line depth found for Mount Prospect in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 42 in. Use the deepest of them until the building department confirms Mount Prospect’s own number.
What frost line depth does Mount Prospect use for footings under Table R301.2(1)? Is it 42 in, like Glenview?
How deep do footings, decks and water lines need to be in Mount Prospect?
Drawn with the deepest nearby official value (42 in). Confirm Mount Prospect’s own depth before you dig.
House or garage footing in Mount Prospect: dig at least 42 in (107 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 42 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 42 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 48 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 42 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 Mount Prospect?
- J
- F
- M
- A
- M
- J
- J
- A
- S
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- N
- D
Average lows are at or below freezing from Dec to Mar. 122 nights a year reach 32 °F or colder; Jan is coldest, with an average low of 18.4 °F.
NOAA 1991–2020 climate normals, Chicago Palwaukee Airport station, 4.3 mi away, elevation 636 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 18.4 | 21.2 | 30.2 | 39.3 | 49.7 | 60.1 | 65.8 | 64.7 | 56.3 | 44.5 | 33.4 | 24 |
| High | 31.9 | 35.8 | 46.7 | 58.1 | 69.5 | 79.5 | 84 | 82 | 75.3 | 62.5 | 48.5 | 36.9 |
Mount Prospect has fewer freezing nights than 43 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 Mount Prospect use?
5 official codes near Mount Prospect are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Glenview | 42 in | 6 mi away |
| Palatine | 42 in | 7 mi away |
| Hoffman Estates | 42 in | 11 mi away |
| Lombard | 42 in | 14 mi away |
| Wheaton | 42 in | 17 mi away |
How likely is the soil in Mount Prospect to heave?
USDA rates the sampled soil around Mount Prospect as 55% moderate, 45% high for frost action (main soils: Orthents, Ashkum, Markham).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Mount Prospect at a glance
- Frost line depth
- No official local value
- County
- Cook County
- Population (2023 est.)
- 54,298
- Mean annual temperature
- 50.8 °F
- ZIP codes (2)
- 60005 · 60056