This week in soil temps
Regional averages from the latest national refresh. Feel free to cite these numbers with a link back to this page.
Northeast
Window passed64°F-5.6°F vs last week
Ranging 47 to 76°F, most of the region is past the spring pre-emergent window.
Southeast
Window passed75°F-9.2°F vs last week
Ranging 60 to 81°F, most of the region is past the spring pre-emergent window.
Midwest
Window passed68°F-8.4°F vs last week
Ranging 54 to 82°F, most of the region is past the spring pre-emergent window.
South Central
Window passed78°F-18.8°F vs last week
Ranging 38 to 87°F, most of the region is past the spring pre-emergent window.
Mountain West
Window passed60°F-25.5°F vs last week
Ranging 38 to 91°F, most of the region is past the spring pre-emergent window.
Pacific
Window passed60°F-22.5°F vs last week
Ranging 41 to 72°F, most of the region is past the spring pre-emergent window.
What the soil temperature bands mean
The timing view groups soil temperatures into five bands. Cool-season lawns (most of the country north of roughly the 33rd parallel) key off a 40 to 50 degree pre-emergent window; warm-season lawns in the South use 50 to 60 degrees.
| Band | Cool-season soil temp | Warm-season soil temp | What to do |
|---|---|---|---|
| Too early | Below 35°F | Below 45°F | Nothing yet. Soil is dormant-cold. |
| Almost time | 35 to 40°F | 45 to 50°F | Buy your pre-emergent and watch the map. |
| Apply pre-emergent now | 40 to 50°F | 50 to 60°F | Apply pre-emergent now, before crabgrass germinates at 55°F. |
| Window closing | 50 to 55°F | 60 to 65°F | Last call. Germination is starting; apply immediately. |
| Window passed | 55°F and up | 65°F and up | Switch to post-emergent control and plan overseeding or fertilizing instead. |
How this map works
A scheduled job refreshes the map every 6 hours from modeled soil temperature data at 6 cm depth (about 2 inches, the depth weed seeds germinate at) via the Open-Meteo weather models, sampled at roughly 1,500 grid points covering the contiguous United States plus 64 metro areas.
The colored surface between grid points is inverse-distance-weighted interpolation, so it is a regional estimate rather than a sensor reading at your address. Regional averages are simple grid-point means (not area-weighted), which slightly overweights northern latitudes; for the 5 degree bands that drive timing decisions the difference is negligible. Timing bands follow the university-extension thresholds used across our tools: pre-emergent goes down before sustained 55 degree soil, with cool-season and warm-season windows shifted accordingly.
Want your exact number instead of a regional estimate? The soil temperature tracker gives you current, historical, and forecast soil temps for your ZIP code, with a timing verdict for your grass type.
Soil temperature map FAQ
What soil temperature should I apply pre-emergent at?
Apply pre-emergent herbicide before soil temperatures reach a sustained 55 degrees F at the 2 inch depth. Crabgrass starts germinating as soil passes 55 degrees, so the ideal window is while soils sit in the 40s for cool-season lawns and the 50s for warm-season lawns. The timing layer on this map shows where that window is open right now.
How is this soil temperature map generated?
The map refreshes every 6 hours from modeled 6 cm (about 2 inch) soil temperature data covering roughly 1,500 grid points across the lower 48 states. Values between grid points are interpolated, so the surface is an estimate rather than a physical sensor reading at your exact address.
Is soil temperature the same as air temperature?
No. Soil warms and cools much more slowly than air. A warm week in late winter can push air temps into the 70s while 2 inch soil stays in the 40s. Lawn timing decisions like pre-emergent, seeding, and fertilizing key off soil temperature, which is why air-temperature forecasts alone lead people to apply too early or too late.
What depth do these soil temperatures represent?
The map shows temperatures at 6 cm, which is about 2 inches deep. That is the depth where crabgrass and most lawn weed seeds germinate, and the depth university extensions reference for pre-emergent and overseeding timing.
What soil temperature does grass seed germinate at?
Cool-season grasses like Kentucky bluegrass, ryegrass, and fescue germinate once soil holds 50 to 65 degrees F. Warm-season grasses like Bermuda and zoysia want 65 to 70 degrees or warmer. Check your exact ZIP on our soil temperature tool for a germination verdict.
How accurate is a modeled soil temperature map?
Modeled soil temperatures track measured station data closely at the regional scale this map is designed for, and the 5 degree bands used for timing decisions absorb most of the local error. Shaded, north-facing, or heavily irrigated yards can run a few degrees off the local estimate, so treat borderline readings as a signal to check with a soil thermometer.
When should I check the map for overseeding timing?
For fall overseeding of cool-season lawns, watch for 2 inch soil temperatures falling back through the 50 to 65 degree range, typically September to early October in the northern half of the country. Spring seeding works when soils climb through that same range.