What to do in Rapid City now
Rapid City is in cool-season grass country. Dates are typical for this spot, worked out from 23 years of weather at Rapid City Regional Ap; each status uses this year's soil estimates.
Cool-season: tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue
- Crabgrass pre-emergent Closed May 14 Typical: Apr 23 – May 152-inch soil held 55°F for a week from May 14, so crabgrass was sprouting. Next window: about Apr 23 – May 15, 2027.
- Seed or overseed Too late this fall Typical: Sep 6 – Oct 134-inch soil fell below 50°F on Oct 30; new seedlings rarely establish now. Seed next fall from about Sep 6, or dormant-seed once soil is near freezing so seed sprouts in spring.
- Late-fall feeding Last call · about 12 days Typical: Oct 20 – Nov 15Top growth has slowed but roots keep feeding until 4-inch soil cools to about 40°F, typically Nov 15. A final nitrogen feeding now goes to the roots.
Warm-season: bermudagrass, zoysia, St. Augustine, centipede, bahia
- Crabgrass pre-emergent Closed May 14 Typical: Apr 23 – May 152-inch soil held 55°F for a week from May 14, so crabgrass was sprouting. Next window: about Apr 23 – May 15, 2027.
- Seed or sod Wait for late spring Typical: Jun 8 – Sep 6Warm-season seed needs 4-inch soil at 65°F or more, and seedlings need the rest of summer to establish. Next window opens about Jun 8.
- Fall pre-emergent (Poa annua) Germinating since Sep 15 Typical: By Sep 44-inch soil fell below 70°F on Sep 15, when annual bluegrass begins to sprout. A pre-emergent now only stops later flushes; plan to apply by about Sep 4 next year.
- Dormancy and last feeding Dormant since about Oct 19 Typical: Around Oct 134-inch soil has stayed under 55°F since Oct 19, so warm-season grass is going brown. It is too late to fertilize; feed again after spring green-up, once soil holds 65°F (typically Jun 8).
The last 60 days and the week ahead
Rapid City soil is 4° warmer than normal for Nov 3, warmer than on 78% of those dates since 2005, and 2° warmer than a year ago.
The green line is our estimate of the daily average soil temperature 2 inches down, driven by temperatures at Rapid City Regional Ap, 13.4 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 20 | 53° | 55° | 77° / 41° | 49° |
| Oct 21 | 55° | 56° | 73° / 43° | 48° |
| Oct 22 | 58° | 58° | 82° / 47° | 48° |
| Oct 23 | 60° | 60° | 84° / 46° | 47° |
| Oct 24 | 54° | 56° | 54° / 29° | 47° |
| Oct 25 | 49° | 52° | 43° / 31° | 46° |
| Oct 26 | 44° | 48° | 35° / 31° | 46° |
| Oct 27 | 45° | 48° | 62° / 31° | 45° |
| Oct 28 | 46° | 48° | 61° / 33° | 45° |
| Oct 29 | 46° | 48° | 61° / 31° | 44° |
| Oct 30 | 45° | 47° | 56° / 33° | 44° |
| Oct 31 | 48° | 49° | 65° / 44° | 44° |
| Nov 1 | 48° | 49° | 55° / 41° | 43° |
| Nov 2 | 48° | 49° | 53° / 41° | 43° |
| Nov 3 | 47° | 49° | 58° / 34° | 43° |
| Nov 4 (forecast) | 46° | 48° | 55° / 34° | 43° |
| Nov 5 (forecast) | 46° | 48° | 56° / 35° | 43° |
| Nov 6 (forecast) | 46° | 48° | 57° / 37° | 43° |
| Nov 7 (forecast) | 47° | 48° | 63° / 37° | 43° |
| Nov 8 (forecast) | 50° | 51° | 70° / 44° | 42° |
| Nov 9 (forecast) | 50° | 51° | 62° / 40° | 42° |
Which grass grows in Rapid City
Rapid City winters are cold enough (January averages 24°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.
Rapid 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 | 33° | 34° | 24° |
| Feb | 34° | 35° | 26° |
| Mar | 38° | 40° | 35° |
| Apr | 45° | 46° | 44° |
| May | 55° | 56° | 54° |
| Jun | 66° | 68° | 65° |
| Jul | 75° | 76° | 73° |
| Aug | 73° | 75° | 71° |
| Sep | 65° | 66° | 61° |
| Oct | 50° | 52° | 47° |
| Nov | 39° | 41° | 35° |
| Dec | 34° | 35° | 26° |
Soil: average of our daily estimates, 2005–2025. Air: NOAA 1991–2020 normals for the station.
Typical lawn dates in Rapid 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) | May 13 | May 20 |
| Crabgrass model: 250 growing degree days | Mar 18 | Feb 14 |
| Pre-emergent window opens (2-inch soil 50°F) | Apr 23 | Mar 22 |
| Crabgrass begins to sprout (2-inch soil 55°F) | May 15 | May 14 |
| Cool-season lawns start growing (4-inch soil 55°F) | May 12 | May 14 |
| Warm-season seeding opens (4-inch soil 65°F) | Jun 8 | May 30 |
| Cool-season seeding opens (4-inch soil under 70°F) | Sep 6 | Sep 17 |
| Cool-season seeding ends (4-inch soil under 55°F) | Oct 13 | Oct 19 |
| Warm-season grass goes dormant (4-inch under 55°F) | Oct 13 | Oct 19 |
| First fall freeze (32°F) | Oct 3 | Oct 16 |
| Roots stop feeding (4-inch soil under 40°F) | Nov 15 | 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 KRAP (RAPID CITY REGIONAL AP), daily data since 1948. Forecast: National Weather Service, UNR office, issued Nov 4, 2026, 5:46 AM EST. Last observed day: Nov 3, 2026.
Rapid City questions
What is the soil temperature in Rapid City today? Our estimate for Nov 3 is 47°F at 2 inches and 49°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 Rapid City? Apply when 2-inch soil holds about 50°F and before it holds 55°F. That has typically been Apr 23 to May 15 in Rapid City. For 2026 the window closed on May 14.
Is it too late to overseed in Rapid City? Too late this fall. 4-inch soil fell below 50°F on Oct 30; new seedlings rarely establish now. Seed next fall from about Sep 6, or dormant-seed once soil is near freezing so seed sprouts in spring.
Is it too late to fertilize in Rapid City? Last call · about 12 days. Top growth has slowed but roots keep feeding until 4-inch soil cools to about 40°F, typically Nov 15. A final nitrogen feeding now goes to the roots.
When is the last frost in Rapid City? The last 32°F night of spring has typically come around May 13, and as late as May 21 in 1 year in 10. The first fall freeze typically arrives around Oct 3.
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.