Soil Temperature Tracker
Monitor current soil temperatures and compare to 5-year and 10-year historical averages. Perfect for timing pre-emergent herbicides, overseeding, and fertilizer applications.
Tool inputs
1 minuteReading and using soil temperature
Air temperature and the date on the calendar lie to you every spring. Soil temperature is what the seeds, roots, and weeds actually respond to.
A warm week in March can fool you into seeding too early, then a cold snap rots the seed in cold ground. The soil holds and releases heat far more slowly than the air, so it tells you what the plants are really experiencing rather than what today happens to feel like.
Two regions on the same calendar date can be weeks apart in soil warmth, which is why a one-size-fits-all spring schedule fails. Reading your local soil temperature replaces guesswork with the one number that drives germination, root growth, and weed-seed sprouting.
Most lawn-care timing decisions hinge on a handful of soil-temperature thresholds, measured at the 2-inch depth.
| Soil temp (2 in) | What it triggers |
|---|---|
| 50–55°F and rising | Apply crabgrass pre-emergent before it climbs past 55°F |
| 55°F | Crabgrass and many summer weeds begin to germinate |
| 55–65°F | Ideal window to seed or overseed cool-season grass |
| 65–70°F | Cool-season grass roots grow fastest; best fall feeding window |
| 65–70°F and rising | Warm-season grass breaks dormancy and greens up |
| 70–80°F | Ideal window to seed or sprig warm-season grass |
Thresholds are guides, not hard lines. Trends matter as much as the single reading: rising into a window is the cue to act.
Depth changes the reading, so the depth has to be standardized.
The 2-inch depth is the agronomic standard for turf because that is where most grass-seed and weed-seed activity happens. Pre-emergent timing and seeding guidance are all calibrated to it.
Deeper soil is more stable and lags the surface, while the top inch swings with every sunny afternoon and cool night. Reading at a fixed 2-inch depth keeps your timing decisions consistent from week to week and comparable to the published thresholds above.
- Morning readings run cooler; mid-afternoon readings run warmer. A consistent time of day gives a cleaner trend.
- Bare or south-facing soil warms faster than shaded or north-facing soil, so your warmest beds wake up before your lawn does.
- A few consecutive days in a window matters more than one reading that briefly pokes into it.
Turn the current reading and the trend line into the next action for your lawn.
- Climbing toward 50°F: get pre-emergent down now, before the crabgrass window opens.
- Holding in the 55–65°F band in early fall: seed or overseed cool-season grass while there is still warmth for establishment.
- Sitting at 65–70°F in fall: this is the highest-leverage feeding window for cool-season lawns.
- Rising past 65°F in late spring: warm-season lawns are ready to seed, sprig, and feed.
Once you know your window, the seeding calculator, herbicide-timing tool, and fertilizer calculator turn the timing into amounts and products for your specific lawn.
Why is soil temperature important for lawn care?
Soil temperature directly affects seed germination, root growth, and nutrient uptake. Cool-season grass seeds germinate best at 50-65°F, while warm-season grasses need 65-75°F. Pre-emergent herbicides work best before soil reaches 55°F.
What depth is the soil temperature measured at?
This tool displays soil temperature at approximately 2 inches (6cm) depth, the standard depth for lawn care decisions where grass seed germinates and most root activity occurs.
When should I apply pre-emergent herbicide?
Apply pre-emergent when soil temperatures consistently reach 50°F but before they hit 55°F. Crabgrass germinates around 55°F, so pre-emergent needs to be in place before that. Most areas have a 2-3 week window.
What's the best soil temperature for overseeding?
Cool-season grasses (Bluegrass, Fescue, Ryegrass): 50-65°F, best in fall. Warm-season grasses (Bermuda, Zoysia, St. Augustine): 65-75°F, best in late spring.
How does soil temperature change with depth?
Surface soil swings widely with air temperature, while deeper soil lags behind. In spring, soil at 8 inches can run 6 to 12°F cooler than the surface; in fall the relationship flips. Lawn-care decisions use the 2-inch reading because that's where grass seed germinates and most root activity happens.
How often does the US soil temperature map update?
The national heatmap refreshes every 6 hours from a fixed grid of about 120 points across the contiguous US. Each point shows the current reading at roughly 2 inches (6cm) of depth, the same depth used for the ZIP-code lookup so the two views stay consistent.
What is the current soil temperature in my area by ZIP code?
Enter your ZIP code in the search box above to pull the current soil temperature for your exact location at the 2-inch depth lawn-care decisions are made at. The reading is sourced from the closest weather grid point, refreshed every 6 hours, and shown alongside 5- and 10-year averages so you can tell whether your soil is running warm, cool, or normal for this date.
What is the average soil temperature by ZIP code for my location?
After you enter a ZIP code, the chart toggles let you overlay 5-year and 10-year average soil temperatures for that exact location. The averages are calculated day-by-day, not as a single annual number, so spring overseeding and pre-emergent timing decisions match the historical pattern for your specific neighborhood rather than a state-wide estimate.
At what soil temperature does crabgrass germinate?
Crabgrass starts germinating when soil temperatures at 2 inches hold above 55°F for several consecutive days, with peak germination from 60-70°F. Apply pre-emergent herbicide when your soil hits the low 50s and is trending up, before the 55°F threshold. Use the ZIP-code lookup above to see whether you're still in the safe window.
What grass-seed germination temperatures should I look for?
Cool-season grasses germinate at the following soil temperatures (2-inch depth): Kentucky Bluegrass 50-65°F, Tall Fescue 50-65°F, Perennial Ryegrass 50-65°F. Warm-season grasses need warmer soil: Bermuda 65-75°F, Zoysia 70-80°F, St. Augustine 70-80°F, Centipede 65-75°F. Use the germination chart above the FAQ to match your current ZIP-code reading to the right seeding window.
Why measure soil temperature at 2 inches and not deeper?
The 2-inch depth is the standard reference for turfgrass decisions because that's where grass seed, crabgrass seed, and pre-emergent herbicide actions take place. Deeper measurements (4-inch, 6-inch) are used for agricultural planting decisions (corn, soybeans) where the seed is buried deeper. For lawn care, every university extension recommendation uses 2-inch soil temperature.
When does my soil temperature reach 50 degrees in spring?
The 50°F threshold (the pre-emergent and cool-season germination trigger) varies by 8 to 10 weeks across the US. Gulf Coast and Southeast typically hit 50°F by mid-February; Mid-Atlantic and Central transition zone by mid-March; Northeast by late March to early April; Great Lakes by mid-April; Upper Midwest by late April to early May. Use the regional table above the FAQ for your area, or enter your ZIP to see this year's actual reading.