The current average 2-inch soil temperature across Idaho is 77°F. Readings range from 72°F to 82°F, from 4 USDA and NOAA monitoring stations. Soil across Idaho is running 4°F below the seasonal normal of 81°F for mid-August, based on 4 of 4 stations with historical records. Idaho spans USDA hardiness zones 5a to 7a, cool-season grass country. Last updated August 16, 2026.
Summer conditions across Idaho with soil averaging 77°F at 2 inches. Warm-season grasses are in peak growth; keep cool-season lawns mowed high and watered deep. The next application windows arrive in fall, starting with pre-emergent as soil falls back through 70°F.
For cool-season lawns (fescue, bluegrass, ryegrass), fall is the best time to plant grass seed in Idaho, with spring the second choice: fall seedlings face less weed competition and mature before summer heat. The window opens as 2-inch soil falls back through 70°F, and germination slows sharply once soil drops below 50°F, typically around October 22.
Spring is the second choice: the window opens when soil first holds 50°F and narrows as soil passes 65°F, typically by June 1.
| Region | Typical spring window opens | Typical fall window opens | Stations |
|---|---|---|---|
| Eastern Idaho | April 30 | September 11 | 2 |
| Central Idaho | April 21 | September 10 | 2 |
Fall seeding also needs a stop date: new seedlings want about six weeks of growth before frost arrives. Your city page estimates the last safe seeding date from its nearest station: see when to plant in Boise, when to plant in Idaho Falls or when to plant in Pocatello. Readings current through August 16, 2026: Idaho averages 77°F at 2 inches right now; the Current Planting Conditions section above reads that number against the season.
Typical dates are computed from historical 2-inch soil temperature averages at 4 monitoring stations in Idaho; your own window depends on your nearest station's readings.
Historical 2-inch soil temperature normals for Idaho: the median across 4 in-state stations with multi-year records. Any given year runs ahead of or behind these values; the live average at the top of this page shows where this year stands.
| Month | Average 2-inch soil temperature |
|---|---|
| January | 33°F |
| February | 34°F |
| March | 40°F |
| April | 48°F |
| May | 59°F |
| June | 72°F |
| July | 84°F |
| August | 77°F |
| September | 66°F |
| October | 52°F |
| November | 38°F |
| December | 35°F |
Grass seed germination
Grass seed germination temperatures across Idaho. Soil warmth varies by location, so check a city page for the live reading and what germinates there now.
| Grass species | Seeding soil temp (2 in) | Days |
|---|---|---|
| Kentucky bluegrass | 50–65°F | 14-30 |
| Tall fescue | 50–65°F | 7-12 |
| Perennial ryegrass | 50–65°F | 5-10 |
| Fine fescue | 50–65°F | 7-14 |
| Bermudagrass | 75–90°F | 10-30 |
For root-zone timing (fertilizer, aeration, weed control), see the 4-inch soil temperature for Idaho. For accumulated-heat timing, see growing degree days for Idaho. For how wet the ground is versus normal, see soil moisture for Idaho. See the Idaho soil temperature map for the full station view.
Interpolated from the latest 4-inch readings and refreshed daily.
| Station | 2" Temp | Last Reading |
|---|---|---|
| Jordan Valley Cwma (Owyhee) | 77°F | 2026-08-16 |
| Orchard Range Site (Ada) | 82°F | 2026-08-16 |
| Arco 17 SW | 72°F | 2026-08-16 |
| Murphy 10 W | 76°F | 2026-08-16 |
Current 2-inch readings grouped along Idaho's east-to-west axis. Regional spread matters for timing: the warm end of the state can open an application window a week or more before the cool end.
| Region | Avg 2" Temp | Range | Stations |
|---|---|---|---|
| Eastern Idaho (Ada County) | 77°F | 72–82°F | 2 |
| Central Idaho (Owyhee County) | 76°F | 76–77°F | 2 |
| City | ZIP | Current Temp |
|---|---|---|
| Boise | 83701 | 82°F |
| Caldwell | 83605 | 76°F |
| Coeur D Alene | 83814 | 72°F |
| Idaho Falls | 83401 | 67°F |
| Meridian | 83642 | 82°F |
| Moscow | 83843 | 73°F |
| Nampa | 83651 | 76°F |
| Pocatello | 83201 | 72°F |
| Post Falls | 83854 | 72°F |
| Rexburg | 83440 | 67°F |
| Sun Valley | 83353 | 72°F |
| Twin Falls | 83301 | 71°F |
Fall is the best time to overseed a thin lawn.
Core aeration relieves compaction, but timing decides whether the lawn recovers in a week or struggles for a month.
Brown patch and Pythium strike when humid nights hold above 68°F on lush, over-fertilized turf; dollar spot, red thread, and rust hit slow-growing lawns at 60-85°F.
Check whether your soil is warm enough for the seed you bought: cool-season grass seeds into 50-65°F soil (tall fescue prefers 60°F and up), warm-season into 75-85°F.
The current average 2-inch soil temperature across Idaho is 77°F. Readings range from 72°F to 82°F depending on location and elevation, from 4 USDA and NOAA monitoring stations. Soil across Idaho is running 4°F below the seasonal normal of 81°F for mid-August, based on 4 of 4 stations with historical records.
Apply pre-emergent herbicide when soil at 2 inches reaches 55°F for several consecutive days. Timing varies across Idaho, so check your city's page for station-specific readings and the pre-emergent timing recommendation.
Idaho spans USDA hardiness zones 5a to 7a, cool-season grass country. For cool-season grasses (fescue, bluegrass), the fall window typically opens around September 11 and the spring window around April 21, based on historical 2-inch soil temperature averages at 4 in-state stations. Timing varies by location, so check your city's planting window for the dates specific to your area.