The current average 2-inch soil temperature across Iowa is 67°F. Readings range from 66°F to 68°F, from 3 USDA and NOAA monitoring stations. Soil across Iowa is right at the seasonal normal of 67°F for mid-September, based on 3 of 3 stations with historical records. Iowa spans USDA hardiness zones 5a to 5b, cool-season grass country. Last updated September 14, 2026.
Soil across Iowa is cooling off its summer peak at an average of 67°F at 2 inches. The fall poa annua pre-emergent window is in play as readings fall through the 65–70°F band, and cool-season overseeding follows close behind.
For cool-season lawns (fescue, bluegrass, ryegrass), fall is the best time to plant grass seed in Iowa, 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 31.
Spring is the second choice: the window opens when soil first holds 50°F and narrows as soil passes 65°F, typically by June 3.
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 Des Moines, when to plant in Cedar Rapids or when to plant in Sioux City. Readings current through September 14, 2026: Iowa averages 67°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 3 monitoring stations in Iowa; your own window depends on your nearest station's readings.
Historical 2-inch soil temperature normals for Iowa: the median across 3 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 | 33°F |
| March | 37°F |
| April | 48°F |
| May | 60°F |
| June | 69°F |
| July | 73°F |
| August | 73°F |
| September | 67°F |
| October | 55°F |
| November | 45°F |
| December | 38°F |
Shaded spring cells fall in the 50°F to 55°F pre-emergent window at 2-inch depth. The highlighted row is the current month.
Grass seed germination
Grass seed germination temperatures across Iowa. 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 | 60–70°F | 14-30 |
| Tall fescue | 60–70°F | 7-12 |
| Perennial ryegrass | 60–70°F | 5-10 |
| Fine fescue | 60–70°F | 7-14 |
| Bermudagrass | 75–90°F | 10-30 |
For root-zone timing (fertilizer, aeration, weed control), see the 4-inch soil temperature for Iowa. For accumulated-heat timing, see growing degree days for Iowa. For how wet the ground is versus normal, see soil moisture for Iowa. See the Iowa soil temperature map for the full station view.
Interpolated from the latest 4-inch readings and refreshed daily.
| Station | 2" Temp | Last Reading |
|---|---|---|
| Ames (Boone) | 66°F | 2026-09-14 |
| Shagbark Hills (Woodbury) | 68°F | 2026-09-14 |
| Des Moines 17 E | 68°F | 2026-09-14 |
| City | ZIP | Current Temp |
|---|---|---|
| Amana | 52203 | 68°F |
| Ames | 50010 | 66°F |
| Ankeny | 50021 | 68°F |
| Bloomfield | 52537 | 70°F |
| Boone | 50036 | 66°F |
| Cedar Falls | 50613 | 66°F |
| Cedar Rapids | 52401 | 63°F |
| Clarion | 50525 | 66°F |
| Clinton | 52732 | 63°F |
| Council Bluffs | 51501 | 70°F |
| Davenport | 52801 | 63°F |
| Des Moines | 50301 | 68°F |
| Dubuque | 52001 | 63°F |
| Fairfield | 52556 | 68°F |
| Harlan | 51537 | 68°F |
| Iowa City | 52240 | 68°F |
| Mason City | 50401 | 66°F |
| Melcher-dallas | 50062 | 68°F |
| Red Oak | 51566 | 70°F |
| Shenandoah | 51601 | 70°F |
| Sioux City | 51101 | 68°F |
| Urbandale | 50322 | 68°F |
| Waterloo | 50701 | 66°F |
| West Des Moines | 50265 | 68°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.
Apply fall pre-emergent when 2-inch soil falls back through 70°F and keeps declining; that crossing is when poa annua and winter annual weeds sprout.
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 Iowa is 67°F. Readings range from 66°F to 68°F depending on location and elevation, from 3 USDA and NOAA monitoring stations. Soil across Iowa is right at the seasonal normal of 67°F for mid-September, based on 3 of 3 stations with historical records.
Apply pre-emergent herbicide when soil at 2 inches reaches 55°F for several consecutive days. Timing varies across Iowa, so check your city's page for station-specific readings and the pre-emergent timing recommendation.
Iowa spans USDA hardiness zones 5a to 5b, cool-season grass country. For cool-season grasses (fescue, bluegrass), the fall window typically opens around September 2 and the spring window around April 13, based on historical 2-inch soil temperature averages at 3 in-state stations. Timing varies by location, so check your city's planting window for the dates specific to your area.