What to do in Iowa City now
Iowa City is in cool-season grass country. Dates are typical for this spot, worked out from 23 years of weather at Iowa City Municipal Ap; each status uses this year's soil estimates.
Cool-season: tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue
- Crabgrass pre-emergent Closed Apr 15 Typical: Apr 10 – Apr 192-inch soil held 55°F for a week from Apr 15, so crabgrass was sprouting. Next window: about Apr 10 – Apr 19, 2027.
- Seed or overseed Seed now · last days Typical: Sep 12 – Oct 21The window usually closes by Oct 21, but this fall has kept 4-inch soil at 60°. Seed only if you can keep it moist, and expect slower germination as soil cools.
- Late-fall feeding Final feeding due now Typical: Oct 31 – Nov 27Not too late. Feed on your normal fall schedule; the last feeding of the year goes down when 4-inch soil falls to about 50°F (typically Oct 31) and before it reaches 40°F (typically Nov 27).
Warm-season: bermudagrass, zoysia, St. Augustine, centipede, bahia
- Crabgrass pre-emergent Closed Apr 15 Typical: Apr 10 – Apr 192-inch soil held 55°F for a week from Apr 15, so crabgrass was sprouting. Next window: about Apr 10 – Apr 19, 2027.
- Seed or sod Wait for late spring Typical: May 20 – Sep 12Warm-season seed needs 4-inch soil at 65°F or more, and seedlings need the rest of summer to establish. Next window opens about May 20.
- Fall pre-emergent (Poa annua) Germinating since Sep 23 Typical: By Sep 114-inch soil fell below 70°F on Sep 23, when annual bluegrass begins to sprout. A pre-emergent now only stops later flushes; plan to apply by about Sep 11 next year.
- Dormancy and last feeding Any day now Typical: Around Oct 21Warm-season grass slows and browns once 4-inch soil stays under 55°F, typically Oct 21. Make the last nitrogen feeding at least a month before that.
The last 60 days and the week ahead
Iowa City soil is 13° warmer than normal for Nov 3, warmer than on 99% of those dates since 2005, and 14° warmer than a year ago.
The green line is our estimate of the daily average soil temperature 2 inches down, driven by temperatures at Iowa City Municipal Ap, 2.1 km from the city center. The dashed part runs the National Weather Service forecast through the same model. Hover or tap for any day.
2-inch soil, estimated From the NWS forecast Normal Normal range (8 years in 10)
Show the numbers
| Date | 2-inch soil | 4-inch soil | Air high / low | Normal (2 in) |
|---|---|---|---|---|
| Oct 21 | 56° | 58° | 75° / 44° | 52° |
| Oct 22 | 58° | 59° | 76° / 47° | 52° |
| Oct 23 | 59° | 60° | 76° / 48° | 51° |
| Oct 24 | 61° | 61° | 77° / 52° | 51° |
| Oct 25 | 61° | 62° | 77° / 48° | 50° |
| Oct 26 | 61° | 62° | 69° / 52° | 49° |
| Oct 27 | 60° | 61° | 67° / 48° | 49° |
| Oct 28 | 60° | 61° | 75° / 46° | 48° |
| Oct 29 | 59° | 60° | 68° / 45° | 48° |
| Oct 30 | 56° | 59° | 58° / 43° | 47° |
| Oct 31 | 56° | 58° | 59° / 52° | 46° |
| Nov 1 | 56° | 58° | – / – | 46° |
| Nov 2 | 57° | 59° | 64° / 58° | 46° |
| Nov 3 | 59° | 60° | 69° / 59° | 46° |
| Nov 4 (forecast) | 56° | 58° | 52° / 46° | 46° |
| Nov 5 (forecast) | 54° | 56° | 54° / 42° | 46° |
| Nov 6 (forecast) | 50° | 53° | 50° / 32° | 47° |
| Nov 7 (forecast) | 48° | 51° | 51° / 35° | 46° |
| Nov 8 (forecast) | 47° | 50° | 57° / 37° | 46° |
| Nov 9 (forecast) | 49° | 51° | 63° / 41° | 45° |
| Nov 10 (forecast) | 50° | 51° | 63° / 42° | 45° |
Which grass grows in Iowa City
Iowa City winters are cold enough (January averages 23°F) that cool-season grasses, mostly Kentucky bluegrass, tall fescue and perennial ryegrass, make up most lawns. They grow in spring and fall and slow down in summer heat.
Iowa City soil through the year
Weekly 2-inch estimates for 2026 so far against 2025 and the normal for each week. The red lines mark 50°F, when crabgrass pre-emergent should be down, and 65°F, when warm-season seed sprouts well.
2026 2025 Normal (2005–2025) 8 years in 10
Normal by month
| Month | 2 in | 4 in | Air |
|---|---|---|---|
| Jan | 32° | 33° | 23° |
| Feb | 33° | 34° | 27° |
| Mar | 40° | 41° | 40° |
| Apr | 51° | 52° | 51° |
| May | 62° | 63° | 63° |
| Jun | 74° | 75° | 72° |
| Jul | 77° | 79° | 76° |
| Aug | 75° | 77° | 74° |
| Sep | 69° | 70° | 66° |
| Oct | 55° | 57° | 53° |
| Nov | 42° | 43° | 40° |
| Dec | 34° | 35° | 28° |
Soil: average of our daily estimates, 2005–2025. Air: NOAA 1991–2020 normals for the station.
Typical lawn dates in Iowa City
Each date is when the soil estimate (or the air, for freezes) crossed the threshold, year by year since 2005. “Early” and “late” are the 10th and 90th percentile years, so 8 years in 10 fall between them.
| Event | Typical | 2026 |
|---|---|---|
| Last spring freeze (32°F) | Apr 25 | Apr 20 |
| Crabgrass model: 250 growing degree days | Mar 23 | Mar 8 |
| Pre-emergent window opens (2-inch soil 50°F) | Apr 10 | Mar 24 |
| Crabgrass begins to sprout (2-inch soil 55°F) | Apr 19 | Apr 15 |
| Cool-season lawns start growing (4-inch soil 55°F) | Apr 18 | Apr 15 |
| Warm-season seeding opens (4-inch soil 65°F) | May 20 | May 19 |
| Cool-season seeding opens (4-inch soil under 70°F) | Sep 12 | Sep 24 |
| Cool-season seeding ends (4-inch soil under 55°F) | Oct 21 | Nov 9 |
| Warm-season grass goes dormant (4-inch under 55°F) | Oct 21 | Nov 9 |
| First fall freeze (32°F) | Oct 21 | not yet |
| Roots stop feeding (4-inch soil under 40°F) | Nov 27 | not yet |
Where these numbers come from
There is no soil sensor in most cities, so we estimate it. Shallow soil follows air temperature with a lag of a few days, and runs a little warmer than the air in fall. We fitted that relationship to 190 USDA soil-sensor stations; on years held out of the fit, the estimate was off by 3.3°F on an average day, and it put the spring 55°F date within a median of 3 days. Read the methodology.
Weather: RCC ACIS station KIOW (IOWA CITY MUNICIPAL AP), daily data since 1948. Forecast: National Weather Service, DVN office, issued Nov 4, 2026, 6:26 AM EST. Last observed day: Nov 3, 2026.
Iowa City questions
What is the soil temperature in Iowa City today? Our estimate for Nov 3 is 59°F at 2 inches and 60°F at 4 inches, as a daily average. Early-morning soil runs a few degrees cooler than that, and afternoon soil warmer.
When should I put down crabgrass pre-emergent in Iowa City? Apply when 2-inch soil holds about 50°F and before it holds 55°F. That has typically been Apr 10 to Apr 19 in Iowa City. For 2026 the window closed on Apr 15.
Is it too late to overseed in Iowa City? Seed now · last days. The window usually closes by Oct 21, but this fall has kept 4-inch soil at 60°. Seed only if you can keep it moist, and expect slower germination as soil cools.
Is it too late to fertilize in Iowa City? Final feeding due now. Not too late. Feed on your normal fall schedule; the last feeding of the year goes down when 4-inch soil falls to about 50°F (typically Oct 31) and before it reaches 40°F (typically Nov 27).
When is the last frost in Iowa City? The last 32°F night of spring has typically come around Apr 25, and as late as May 5 in 1 year in 10. The first fall freeze typically arrives around Oct 21.
Why 2 inches and 4 inches? Crabgrass and most weed seeds sprout in the top inch or two, so pre-emergent timing follows 2-inch soil. Grass seed and roots respond to the slightly steadier soil at about 4 inches.
How accurate is this? It is a model, not a probe in your yard. Expect about 3–4°F of difference on a given day; shade, slope, mulch and irrigation all move real soil. The dates and trends are more reliable than any single day.