What to do in Boise City now
Boise City is in cool-season grass country. Dates are typical for this spot, worked out from 23 years of weather at Boise Air Terminal; each status uses this year's soil estimates.
Cool-season: tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue
- Crabgrass pre-emergent Closed Mar 24 Typical: Apr 5 – Apr 292-inch soil held 55°F for a week from Mar 24, so crabgrass was sprouting. Next window: about Apr 5 – Apr 29, 2027.
- Seed or overseed Late · risky Typical: Sep 20 – Oct 20Soil fell below 55°F on Oct 29. Seed sown now germinates slowly and may not survive winter. The hard stop, 4-inch soil under 50°F, typically comes around Nov 3.
- Late-fall feeding Final feeding due now Typical: Nov 3 – Nov 26Not 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 Nov 3) and before it reaches 40°F (typically Nov 26).
Warm-season: bermudagrass, zoysia, St. Augustine, centipede, bahia
- Crabgrass pre-emergent Closed Mar 24 Typical: Apr 5 – Apr 292-inch soil held 55°F for a week from Mar 24, so crabgrass was sprouting. Next window: about Apr 5 – Apr 29, 2027.
- Seed or sod Wait for late spring Typical: May 23 – Sep 20Warm-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 23.
- Fall pre-emergent (Poa annua) Germinating since Sep 7 Typical: By Sep 194-inch soil fell below 70°F on Sep 7, when annual bluegrass begins to sprout. A pre-emergent now only stops later flushes; plan to apply by about Sep 19 next year.
- Dormancy and last feeding Dormant since about Oct 29 Typical: Around Oct 204-inch soil has stayed under 55°F since Oct 29, 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 May 23).
The last 60 days and the week ahead
Boise City soil is 0° cooler than normal for Nov 3, cooler than on 52% of those dates since 2005, and 1° cooler than a year ago.
The green line is our estimate of the daily average soil temperature 2 inches down, driven by temperatures at Boise Air Terminal, 3.8 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 | 60° | 61° | 75° / 46° | 55° |
| Oct 21 | 61° | 62° | 78° / 54° | 54° |
| Oct 22 | 62° | 63° | 75° / 50° | 54° |
| Oct 23 | 58° | 60° | 57° / 38° | 53° |
| Oct 24 | 54° | 57° | 58° / 33° | 52° |
| Oct 25 | 53° | 56° | 65° / 39° | 52° |
| Oct 26 | 52° | 55° | 61° / 40° | 51° |
| Oct 27 | 51° | 54° | 57° / 39° | 50° |
| Oct 28 | 50° | 52° | 58° / 35° | 49° |
| Oct 29 | 50° | 52° | 63° / 37° | 49° |
| Oct 30 | 50° | 52° | 61° / 39° | 48° |
| Oct 31 | 51° | 52° | 63° / 42° | 48° |
| Nov 1 | 50° | 52° | 55° / 42° | 48° |
| Nov 2 | 48° | 50° | 56° / 34° | 48° |
| Nov 3 | 47° | 50° | 53° / 38° | 48° |
| Nov 4 (forecast) | 48° | 50° | 58° / 39° | 47° |
| Nov 5 (forecast) | 47° | 49° | 56° / 33° | 47° |
| Nov 6 (forecast) | 47° | 49° | 59° / 36° | 47° |
| Nov 7 (forecast) | 49° | 50° | 64° / 42° | 46° |
| Nov 8 (forecast) | 50° | 51° | 65° / 40° | 45° |
| Nov 9 (forecast) | 50° | 51° | 64° / 41° | 45° |
Which grass grows in Boise City
Boise City winters are cold enough (January averages 32°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.
Boise 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 | 34° | 35° | 32° |
| Feb | 37° | 38° | 38° |
| Mar | 44° | 45° | 45° |
| Apr | 51° | 52° | 51° |
| May | 60° | 61° | 60° |
| Jun | 70° | 71° | 68° |
| Jul | 80° | 82° | 77° |
| Aug | 79° | 81° | 76° |
| Sep | 69° | 71° | 66° |
| Oct | 55° | 57° | 53° |
| Nov | 42° | 44° | 40° |
| Dec | 35° | 36° | 32° |
Soil: average of our daily estimates, 2005–2025. Air: NOAA 1991–2020 normals for the station.
Typical lawn dates in Boise 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 23 | Apr 17 |
| Crabgrass model: 250 growing degree days | Mar 1 | Feb 15 |
| Pre-emergent window opens (2-inch soil 50°F) | Apr 5 | Mar 20 |
| Crabgrass begins to sprout (2-inch soil 55°F) | Apr 29 | Mar 24 |
| Cool-season lawns start growing (4-inch soil 55°F) | Apr 26 | Mar 24 |
| Warm-season seeding opens (4-inch soil 65°F) | May 23 | May 12 |
| Cool-season seeding opens (4-inch soil under 70°F) | Sep 20 | Sep 8 |
| Cool-season seeding ends (4-inch soil under 55°F) | Oct 20 | Oct 29 |
| Warm-season grass goes dormant (4-inch under 55°F) | Oct 20 | Oct 29 |
| First fall freeze (32°F) | Oct 24 | not yet |
| Roots stop feeding (4-inch soil under 40°F) | Nov 26 | not yet |
Checked against a real sensor
Measured nearby: 47°F at 2 inches on Nov 3, at the USDA SCAN site “Orchard Range Site”, 22 miles away.
Our estimate for Boise City on Nov 3 is 47°F; the sensor read 51°F at 4 inches against our 50°F. Sensor sites sit in open, unwatered ground outside town, so they often run a few degrees apart from city lawns; use them as a check on the trend.
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 KBOI (BOISE AIR TERMINAL), daily data since 1940. Forecast: National Weather Service, BOI office, issued Nov 4, 2026, 1:29 AM EST. Last observed day: Nov 3, 2026.
Boise City questions
What is the soil temperature in Boise City today? Our estimate for Nov 3 is 47°F at 2 inches and 50°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 Boise City? Apply when 2-inch soil holds about 50°F and before it holds 55°F. That has typically been Apr 5 to Apr 29 in Boise City. For 2026 the window closed on Mar 24.
Is it too late to overseed in Boise City? Late · risky. Soil fell below 55°F on Oct 29. Seed sown now germinates slowly and may not survive winter. The hard stop, 4-inch soil under 50°F, typically comes around Nov 3.
Is it too late to fertilize in Boise 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 Nov 3) and before it reaches 40°F (typically Nov 26).
When is the last frost in Boise City? The last 32°F night of spring has typically come around Apr 23, and as late as May 10 in 1 year in 10. The first fall freeze typically arrives around Oct 24.
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.