Conditions, history, and source details
79
Soil Temps location estimate. The nearest of 337 active USDA and NOAA in-ground stations (Merced 23 WSW, 96 mi away) is too far to represent local soil, so Soil Temps publishes a daily estimate for these coordinates instead.
Planning the year
See Vacaville scheduleFertilizer
A foliar iron spray darkens the lawn's color without forcing the leaf growth a nitrogen feeding would, which is exactly what summer-stressed turf needs. Iron is taken up directly through the leaves, so results show in days rather than weeks. Shallow soil temperatures are in the action band at 79°F at 2 inches from the modeled estimate.
Source: Modeled soil-temperature estimate
Pest Watch
White grubs are the larvae of Japanese beetles, June bugs, and similar species, and they feed on grass roots through summer. Catching the first generation in early summer, before significant root damage, makes preventive insecticide much more effective than rescue treatments. Shallow soil temperatures are in the action band at 79°F at 2 inches from the modeled estimate.
Source: Modeled soil-temperature estimate
Depth: 2" • 28 days of data • Modeled estimate
Merced 23 WSW (Site USCRN-93243), CA
Estimated Soil Temperatures
| Date | 2" °F | Δ 2" | 8" °F | 20" °F |
|---|---|---|---|---|
| Aug 19 | 79.1 | +1.6 | 77.4 | 74.5 |
| Aug 18 | 77.5 | -0.2 | 76.3 | 74.3 |
| Aug 17 | 77.7 | +1.6 | 76.5 | 74.1 |
| Aug 16 | 76.1 | +2.8 | 74.7 | 74.1 |
| Aug 15 | 73.3 | +0.8 | 73.4 | 74.5 |
| Aug 14 | 72.5 | -0.6 | 73.6 | 75.1 |
| Aug 13 | 73.1 | — | 75.2 | 75.8 |
Soil temperature by depth
These soil temperatures are Soil Temps location estimates, updated daily. The nearest of 337active USDA and NOAA in-ground stations is too far away to represent this location’s soil.
Zone 9B
November 28
875 ft
Warm-season only
This area favors warm-season grasses; cool-season grass struggles through the summer heat here. As of August 19, the 2-inch soil temperature is running 3°F above the 10-year normal for this date. A current federal soil-station reading was unavailable, so values here are modeled estimates. Use them as a directional guide.
For established lawns and gardens, the 4 inch soil temperature is a more useful reading than the surface. This 4-inch root-zone depth changes more slowly than the 2-inch surface layer, so it is a steadier signal for timing fertilizer, aeration, and weed control. The depths your nearest station reports are shown above; stations in the federal network typically report 2, 4, 8, 20, and 40 inches, while modeled estimates for areas far from a station cover fewer depths.
This week’s watering for Vacaville, CA
Water about 1.25 inches this week
| Weekly target | 1.25 in | at 79°F soil, for warm-season grass |
|---|---|---|
| Expected rain | 0 in | over the next 7 days |
| You supply | 1.25 in | in 2 deep sessions, watered 4-9 AM |
The weekly target includes rainfall, so irrigation only covers the deficit. Water deeply and infrequently rather than a little every day: shallow daily watering builds shallow roots and invites disease. Rainfall is a modeled forecast estimate for this location.
How to water by soil temperature, and audit your sprinklers →
Lawn disease risk
The 7-day forecast near Vacaville, CA favors watch-level conditions. These diseases are the ones to watch now. Based on a modeled weather estimate for this location.
| Disease | Risk | Why now |
|---|---|---|
| Dollar spot (Clarireedia jacksonii) | Watch | 4 of the next 7 days sit in its 60-85°F window; worse on underfed turf. Keep adequate nitrogen and remove morning dew (early mowing or dragging a hose) to shorten the wetness window. |
| Rust (Puccinia spp.) | Watch | 4 of the next 7 days sit in its 65-85°F window; worse on underfed turf. Feed adequately and irrigate early so foliage dries fast; adequate nitrogen lets turf outgrow rust's slow cycle. |
How temperature drives lawn disease, and the cultural fixes →
Growing degree days near Vacaville, CA
Michigan State ground-truthed these models in the Great Lakes region and does not recommend them for the mid-south transition zone or the South. Outside the Upper Midwest and Northeast, read them as a guide and confirm against local extension guidance.
Growing degree days measure the heat a lawn has accumulated this year: each day adds the amount its average temperature runs above 50°F, the point where cool-season growth and most pests get going. Turf managers use the running total to time crabgrass pre-emergent, annual bluegrass seedhead suppression, and grub control. Pairing it with the current soil temperature shows both the season's heat so far and what the ground is doing right now. Measured at the NOAA station Merced 23 WSW.
Soil temperature readings on this page cover 3 ZIP codes in Vacaville, CA:
95687, 95688, 95696
Know when to seed, fertilize, and stop crabgrass at your address, timed by live local soil temperature instead of the calendar.
Check the current soil temp at your location, or open the live US soil temperature mapto see today’s ground readings from 380+ USDA and NOAA stations across the country. Enter your city or ZIP code for live soil temperatures near you, plus planting windows, pre-emergent timing, fertilizer guidance, and disease watch alerts for your area.
Readings refresh nightly from the USDA-NRCS Soil Climate Analysis Network and the NOAA US Climate Reference Network (USCRN). Where a current suitable station reading is unavailable, readings are modeled estimates rather than direct sensor measurements; see how we measure. Planting windows are derived from multi-year climatology, overlaid with NOAA 1991–2020 frost normals where a station is close enough to support a local frost date. Recommendation cards evaluate current soil conditions against research-backed thresholds from university extension sources. Check back regularly as conditions change. The guidance updates with every new reading.
Data sources: USDA-NRCS SCAN network, NOAA USCRN, NOAA 1991–2020 climate normals, and localized frost climatology via Soil Temps analytics.
Browse soil temperature data by state, over 2,000 cities with current readings, hardiness zones, and planting windows.
Explore the US Soil Temperature Map for a live station view of readings across the country.
Current soil temperature: 79°F at the 2-inch depth, 3.3°F above the historical average for this date. Modeled estimate for August 19, 2026; a current monitoring-station reading was unavailable. Rising 6°F over the last 7 days.
Current conditions in Vacaville, CA
79°F
2-inch depth
A foliar iron spray darkens the lawn's color without forcing the leaf growth a nitrogen feeding would, which is exactly what summer-stressed turf needs. Iron is taken up directly through the leaves, so results show in days rather than weeks. Shallow soil temperatures are in the action band at 79°F at 2 inches from the modeled estimate.
View detailsThe forecast adds 0 inches of rain. Apply the remaining deficit in 2 deep sessions.
View detailsThe 2-inch reading is 79°F. Check the species table before deciding whether to seed.
View detailsAir and rain
Weather context
For warm-season grasses, yes. The 2-inch soil temperature near Vacaville, CA is currently 79.1°F, a Soil Temps location estimate for these coordinates; the nearest in-ground station (Merced 23 WSW) is 96.4 miles away. That is at or above the 65°F threshold where Bermuda and zoysia establish, and above the 50–65°F cool-season band, so hold cool-season seeding until soil cools back through 65°F.
Soil temperature outside the germination band is the most common cause. The 2-inch soil temperature near Vacaville, CA is currently 79.1°F, a Soil Temps location estimate for these coordinates; the nearest in-ground station (Merced 23 WSW) is 96.4 miles away. Cool-season seed germinates at 50–65°F and warm-season seed at 65°F or higher; outside those bands seed sits dormant rather than sprouting. If the temperature is right, the usual culprits are seed buried too deep, topsoil that dried out during the sprout window, or a pre-emergent herbicide applied the same season, which blocks grass seed the same way it blocks weeds.
Cool-season grasses like fescue and bluegrass germinate best when soil at 2 inches stays between 50–65°F for several consecutive days. Warm-season grasses like Bermuda and Zoysia need soil temperatures of 65°F or higher before seeding. If you are seeding, a high-phosphorus starter fertilizer goes down in the same window; regular established-lawn fertilizer follows different timing.
Apply pre-emergent herbicide, the product sold at retail as crabgrass preventer, when soil at 2 inches reaches 55°F for several consecutive days. This is the threshold where crabgrass and other summer annual weeds begin germinating, and applying after that point reduces effectiveness significantly. Weed-and-feed products that include a pre-emergent follow the same window. The pre-emergent timing page for Vacaville tracks this threshold against the current reading.
Vacaville, CA is in USDA hardiness zone 9b, mild enough that warm-season grasses like Bermuda, zoysia, and St. Augustine come through winter reliably; they go tan and dormant rather than dying. Cool-season grasses survive winter here easily but struggle through the hot summer instead.
Use 2 inches for germination decisions, since that is where seeds sit. Use the 4 inch soil temperature for established lawn and garden timing: it reads the root zone, changes more slowly than the surface, and is the depth most fertilizer, aeration, and disease guidance references. The 8 inch reading shows deeper root-zone trend. The 20 and 40 inch readings track deep soil and frost depth where federal stations report them.
Soil changes temperature much more slowly than air due to thermal mass. A warm afternoon does not mean the ground is warm. Soil temperature lags air temperature by days or weeks, making it a more reliable indicator of when biological processes like germination actually begin.
It is a Soil Temps location estimate, updated daily and labeled as such. The 2-inch soil temperature near Vacaville, CA is currently 79.1°F, a Soil Temps location estimate for these coordinates; the nearest in-ground station (Merced 23 WSW) is 96.4 miles away. Soil Temps publishes an estimate when the nearest of 337 active USDA and NOAA in-ground monitoring stations is too far away to represent local soil, instead of presenting a faraway station's reading as local truth.
Each window above is counted on its own base temperature and start date, which is why those numbers differ from the headline total. A target range means nothing without them.
Grass seed germination
Your soil near Vacaville, CA: 79°F at 2 inches, as of August 19, 2026. Soil Temps location estimate.
| Grass species | Seeding soil temp (2 in) | Days | Right now |
|---|---|---|---|
| Bermudagrass | 75–90°F | 10-30 | Germinates well |
| Zoysia | 75–90°F | varies | Germinates well |
| Buffalograss | 75–90°F | 14-30 | Germinates well |
| Centipede | 75–90°F | varies | Germinates well |
| Kentucky bluegrass | 60–70°F | 14-30 | Too warm to establish |