Helena, Montana · Nov 11, 2026
Soil temperature today in Helena
low 45°F · high 50°F
Modelled by NOAA GFS · run Nov 11, 12:00 UTC (7 am Eastern) · grid cell 10.7 km from Helena
What the soil says today
- Pre-emergentSeason over
- Cool-season seedToo late in the season
- Warm-season seedToo cold
- TomatoesToo cold
- Peas and lettuceWarm enough
From the 5-day mean of the modelled 0–4 in layer.
Soil temperature, 0–4 in: last 7 days and next 7
°F. Dots and line: daily average (dashed = forecast); bars: the day's low to high; green band: the 50–55°F pre-emergent window.
- Daily average
- Low to high
- 50–55°F window
View as table
| Day | Average | Low | High | |
|---|---|---|---|---|
| Nov 4 | 38.8°F | 36.8°F | 42.5°F | analysis |
| Nov 5 | 39.1°F | 36.8°F | 42.2°F | analysis |
| Nov 6 | 39.7°F | 37.2°F | 43.7°F | analysis |
| Nov 7 | 44.0°F | 41.5°F | 48.5°F | analysis |
| Nov 8 | 45.8°F | 42.9°F | 50.0°F | analysis |
| Nov 9 | 44.0°F | 41.8°F | 46.3°F | analysis |
| Nov 10 | 44.2°F | 42.4°F | 47.3°F | analysis |
| Today | 46.7°F | 44.7°F | 50.4°F | forecast |
| Nov 12 | 46.3°F | 44.5°F | 48.4°F | forecast |
| Nov 13 | 43.8°F | 41.8°F | 46.5°F | forecast |
| Nov 14 | 43.5°F | 41.5°F | 46.4°F | forecast |
| Nov 15 | 41.2°F | 38.7°F | 44.1°F | forecast |
| Nov 16 | 40.0°F | 37.7°F | 42.8°F | forecast |
| Nov 17 | 40.5°F | 39.0°F | 42.7°F | forecast |
What the soil says for each job
Today's verdicts use the 5-day mean of the modelled 0–4 in layer.
| Job | Soil rule | Today |
|---|---|---|
| Crabgrass pre-emergent | Apply while the soil holds 50 to 55°F, before crabgrass germinates at about 55°F | Season over The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from May 24 and 55°F from Jun 16. |
| Seed or overseed cool-season grass | Fescue, bluegrass and ryegrass germinate best in soil of 50 to 65°F | Too late in the season Past the usual Aug 15 to Oct 15 seeding window (45°F soil today). |
| Seed warm-season grass | Bermuda, zoysia and centipede need soil of 65°F or more | Too cold 45°F: under 65°F. |
| Plant out tomatoes | Tomato roots want soil of 60°F or more (check your frost date as well) | Too cold 45°F: under 60°F. |
| Sow peas, lettuce and spinach | Cool-weather crops germinate once soil reaches about 40°F | Warm enough 45°F: at or over 40°F. |
The 2026 season so far
°F, daily average of the 0–4 in layer since 1 January (dashed = forecast). Dots: the days the soil began to hold 50°F and 55°F.
- Daily average
- 50–55°F window
When the soil crossed each threshold
2026, from the 5-day mean held for 10 days or more.
| Soil | What it means | Held from (spring 2026) | Fell below (autumn 2026) |
|---|---|---|---|
| 40°F | Peas and lettuce can be sown | Mar 20 | Oct 28 |
| 50°F | Pre-emergent window opens | May 24 | Oct 24 |
| 55°F | Crabgrass can germinate | Jun 16 | Oct 12 |
| 60°F | Warm enough for tomatoes | not reached | Sep 9 |
| 65°F | Warm-season grass seed | not reached | Sep 1 |
Growing degree days in Helena
Base 50°F, from 1 January to Nov 8, at the Helena Airport Asos station (3.8 km).
A growing degree day is each degree that the day's average temperature runs above 50°F. Insects, weeds and crops develop by accumulated GDD, so the number says how far the season has run. Every city.
Soil temperature nearby
Each from a different model grid cell.
| City | Distance | Soil today | vs a week ago | Grass seed |
|---|---|---|---|---|
| Butte, MT | 76 km | 40°F | +6°F | Too late in the season |
| Great Falls, MT | 115 km | 50°F | +10°F | Too late in the season |
| Bozeman, MT | 127 km | 44°F | +7°F | Too late in the season |
| Missoula, MT | 152 km | 45°F | +8°F | Too late in the season |
| Kalispell, MT | 247 km | 45°F | +10°F | Too late in the season |
Questions
- What is the soil temperature in Helena today?
- About 47°F on average in the top 4 inches (0–10 cm), with a low of 45°F and a high of 50°F, from NOAA's GFS model run of Nov 11, 12:00 UTC (7 am Eastern).
- Is it time to put down crabgrass preventer in Helena?
- The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from May 24 and 55°F from Jun 16.
- When did the soil in Helena reach 55°F this year?
- The 5-day average held 55°F from Jun 16, 2026.
- How accurate is a modelled soil temperature?
- Against NOAA's 108 reference stations the model's daily average was off by 4.2°F on average, and within 5°F on 68% of days. A shaded, mulched or watered yard can differ more.
Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); U.S. Climate Reference Network (USCRN) hourly data, version 2 (soil temperature at 5 cm and 10 cm, air temperature) (NOAA National Centers for Environmental Information (NCEI)); Global Historical Climatology Network - Daily (GHCN-Daily), daily maximum and minimum temperature (NOAA National Centers for Environmental Information (NCEI)); GeoNames gazetteer (cities15000) (GeoNames).