Frost Line Depth in Rialto, California
- 4 verified codes nearby
- Checked Oct 2026
No official local value
Frost rarely reaches the ground in Rialto.
Nearby official codes require 12 in (4 verified codes).
Footings still go at least 12 in (30 cm) below undisturbed ground (IRC R403.1.4).
Source and how we checked
We searched this place’s own code and website and found no published frost line depth.
Climate: 2 nights a year at or below 32 °F (NOAA 1991–2020, Riverside Citrus Exp, 10.5 mi).
Checked Oct 2026. Report a correction
Does Rialto have an official frost line depth?
No adopted frost line depth found for Rialto in its official documents (checked Oct 2026). The nearest official values, from codes we verified, are 12 in. Use the deepest of them until the building department confirms Rialto’s own number.
What frost line depth does Rialto use for footings under Table R301.2(1)? Is it 12 in, like Chino?
How deep do footings, decks and water lines need to be in Rialto?
Drawn with the deepest nearby official value (12 in). Confirm Rialto’s own depth before you dig.
House or garage footing in Rialto: dig at least 12 in (30 cm). Below the frost line and at least 12 in deep (IRC R403.1.4).
| Project | Depth | Rule |
|---|---|---|
| House or garage footing | 12 in | Below the frost line and at least 12 in deep (IRC R403.1.4) |
| Deck footing (attached) | 12 in | Below the frost line and at least 12 in deep (IRC R507.3) |
| Water service line | 18 in | 6 in below the frost line and at least 12 in deep (IRC P2603.5) |
| Fence post bottom | 12 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 Rialto?
- J
- F
- M
- A
- M
- J
- J
- A
- S
- O
- N
- D
Rialto never averages a low below freezing. 2 nights a year reach 32 °F or colder; Dec is coldest, with an average low of 43.2 °F.
NOAA 1991–2020 climate normals, Riverside Citrus Exp station, 10.5 mi away, elevation 986 ft.
Monthly temperatures as a table
| °F | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Low | 44.2 | 44.8 | 46.9 | 49.9 | 54.8 | 58.4 | 62.9 | 63.7 | 60.8 | 54.8 | 47.4 | 43.2 |
| High | 69.5 | 69.9 | 72.3 | 75.1 | 80.4 | 87.4 | 94.1 | 96.6 | 93.4 | 81.9 | 76.1 | 69.1 |
Rialto has fewer freezing nights than 114 of the 208 other California places we track. The California median is 3. Coldest: El Dorado County; mildest: San Diego.
What frost line depth do towns near Rialto use?
4 official codes near Rialto are verified; each links to its document.
| Place | Verified frost line | Distance |
|---|---|---|
| Chino | 12 in | 18 mi away |
| Glendora | 12 in | 26 mi away |
| Mission Viejo | 12 in | 38 mi away |
| Whittier | 12 in | 38 mi away |
How likely is the soil in Rialto to heave?
USDA rates the sampled soil around Rialto as 100% none for frost action (main soils: Tujunga, Hanford, Soboba).
USDA NRCS soil survey, 9 sample points within 2 mi. Higher frost action means more risk of heave; see frost heave.
Rialto at a glance
- Frost line depth
- No official local value
- County
- San Bernardino County
- Population (2023 est.)
- 103,391
- Mean annual temperature
- 66.6 °F
- ZIP codes (9)
- 92316 · 92324 · 92335 · 92336 · 92376 · 92377 · 92407 · 92410 · 92411