4-Inch Soil Temperature in Iowa
The current average 4-inch soil temperature across Iowa is 65°F, measured at 3 USDA and NOAA monitoring stations. Readings range from 63°F to 66°F. Soil across Iowa is right at the seasonal normal of 64°F for late September, based on 3 of 3 stations with historical records. Last updated September 23, 2026.
Why the 4-Inch Reading
Every reading here is measured at native 4-inch depth by USDA SCAN (Soil Climate Analysis Network) and NOAA USCRN (US Climate Reference Network) stations, not modeled. The 4-inch root-zone temperature changes more slowly than the surface, making it the steadier signal for established-lawn and garden timing: pre-emergent and broadleaf herbicide windows, fertilizer applications, and core aeration.
Stations Measuring 4-Inch Depth in Iowa (3)
| Station | 4" Temp | Last Reading |
|---|---|---|
| Ames (Boone) | 63°F | 2026-09-23 |
| Shagbark Hills (Woodbury) | 66°F | 2026-09-23 |
| Des Moines 17 E | 66°F | 2026-09-23 |
Cities in Iowa (24)
| City | ZIP | Current Temp |
|---|---|---|
| Amana | 52203 | 66°F |
| Ames | 50010 | 63°F |
| Ankeny | 50021 | 66°F |
| Bloomfield | 52537 | 66°F |
| Boone | 50036 | 63°F |
| Cedar Falls | 50613 | 63°F |
| Cedar Rapids | 52401 | 66°F |
| Clarion | 50525 | 63°F |
| Clinton | 52732 | — |
| Council Bluffs | 51501 | 66°F |
| Davenport | 52801 | — |
| Des Moines | 50301 | 66°F |
| Dubuque | 52001 | — |
| Fairfield | 52556 | 66°F |
| Harlan | 51537 | 66°F |
| Iowa City | 52240 | 66°F |
| Mason City | 50401 | 63°F |
| Melcher-dallas | 50062 | 66°F |
| Red Oak | 51566 | — |
| Shenandoah | 51601 | — |
| Sioux City | 51101 | 66°F |
| Urbandale | 50322 | 66°F |
| Waterloo | 50701 | 63°F |
| West Des Moines | 50265 | 66°F |
4-Inch Soil Temperature FAQ for Iowa
What is the current 4-inch soil temperature in Iowa?
The current average 4-inch soil temperature across Iowa is 65°F, measured at 3 USDA and NOAA stations. Readings range from 63°F to 66°F depending on location and elevation. Soil across Iowa is right at the seasonal normal of 64°F for late September, based on 3 of 3 stations with historical records.
What does the 4 inch soil temperature mean?
The 4 inch soil temperature shows conditions deeper in the root zone than the 2 inch germination reading. It is commonly used for established lawn, garden, and agricultural timing because it changes more slowly than the surface layer, so it is a steadier signal for fertilizer, aeration, and weed-control decisions.
Why use 4-inch soil temperature instead of 2-inch?
Use 2 inches for germination decisions, since that is where seeds sit. Use the 4 inch soil temperature for established lawn and garden timing: it reads the root zone, changes more slowly than the surface, and is the depth most fertilizer, aeration, and disease guidance references.
See the national 4-inch soil temperature map, the full Iowa soil temperature directory (all depths), the national soil temperature by depth comparison, or the live national soil temperature map.