4-Inch Soil Temperature in Maine
The current average 4-inch soil temperature across Maine is 55°F, measured at 2 USDA and NOAA monitoring stations. Readings range from 55°F to 55°F. Soil across Maine is running 4°F below the seasonal normal of 59°F for late September, based on 2 of 2 stations with historical records. Last updated September 26, 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 Maine (2)
| Station | 4" Temp | Last Reading |
|---|---|---|
| Old Town 2 W | 55°F | 2026-09-26 |
| Limestone 4 NNW | 55°F | 2026-09-26 |
Cities in Maine (15)
| City | ZIP | Current Temp |
|---|---|---|
| Auburn | 04210 | 55°F |
| Augusta | 04330 | 55°F |
| Bangor | 04401 | 55°F |
| Biddeford | 04005 | — |
| Castine | 04420 | 55°F |
| Freeport | 04032 | — |
| Lewiston | 04240 | 55°F |
| Limestone | 04750 | 55°F |
| New Portland | 04954 | 55°F |
| Orono | 04469 | 55°F |
| Portland | 04101 | — |
| Scarborough | 04070 | — |
| South Portland | 04106 | — |
| Waterville | 04901 | 55°F |
| Westbrook | 04092 | — |
4-Inch Soil Temperature FAQ for Maine
What is the current 4-inch soil temperature in Maine?
The current average 4-inch soil temperature across Maine is 55°F, measured at 2 USDA and NOAA stations. Readings range from 55°F to 55°F depending on location and elevation. Soil across Maine is running 4°F below the seasonal normal of 59°F for late September, based on 2 of 2 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 Maine soil temperature directory (all depths), the national soil temperature by depth comparison, or the live national soil temperature map.