What to do in Harlingen now
Harlingen is in warm-season grass country. Dates are typical for this spot, worked out from 23 years of weather at Harlingen Rio Grande Valley Intl Ap; each status uses this year's soil estimates.
Cool-season: tall fescue, Kentucky bluegrass, perennial ryegrass, fine fescue
- Crabgrass pre-emergent No clear spring window Typical: Soil rarely drops below 55°FSoil here stays warm enough for crabgrass to sprout in most months. Extension calendars in frost-free areas usually time a late-winter pre-emergent application by date rather than by soil temperature.
- Seed or overseed Soil rarely cools enough Typical: –4-inch soil here seldom falls into the 55–70°F seeding range for long. Cool-season grasses struggle in this climate; tall fescue is the usual exception, seeded in the coolest months.
- Late-fall feeding Soil rarely cools to 40°F Typical: Through winterRoots stay active through most winters here. Feed on the fall schedule your extension office gives for your grass, and avoid feeding a lawn that is dormant from drought.
Warm-season: bermudagrass, zoysia, St. Augustine, centipede, bahia
- Crabgrass pre-emergent No clear spring window Typical: Soil rarely drops below 55°FSoil here stays warm enough for crabgrass to sprout in most months. Extension calendars in frost-free areas usually time a late-winter pre-emergent application by date rather than by soil temperature.
- Seed or sod Seed or sod now Typical: Feb 11 – Nov 204-inch soil is 85°. Seed planted later than late summer has little warm weather left to establish before dormancy.
- Fall pre-emergent (Poa annua) Apply within 10 days Typical: By Nov 13Annual bluegrass (Poa annua) starts sprouting when 4-inch soil falls below 70°F, typically Nov 13. A fall pre-emergent must be down before then. Skip it if you plan to overseed with ryegrass.
- Dormancy Rarely goes dormant Typical: Grows most of the yearSoil stays warm enough here that warm-season grass slows in winter rather than going fully dormant.
The last 60 days and the week ahead
Harlingen soil is 12° warmer than normal for Nov 3, warmer than on 100% of those dates since 2005, and 16° warmer than a year ago.
The green line is our estimate of the daily average soil temperature 2 inches down, driven by temperatures at Harlingen Rio Grande Valley Intl Ap, 6 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 21 | 85° | 86° | – / – | 77° |
| Oct 22 | 85° | 86° | – / – | 76° |
| Oct 23 | 85° | 86° | – / – | 76° |
| Oct 24 | 85° | 86° | – / – | 76° |
| Oct 25 | 85° | 86° | – / – | 75° |
| Oct 26 | 85° | 86° | – / – | 75° |
| Oct 27 | 85° | 86° | – / – | 74° |
| Oct 28 | 85° | 86° | – / – | 74° |
| Oct 29 | 85° | 86° | – / – | 73° |
| Oct 30 | 85° | 86° | – / – | 73° |
| Oct 31 | 85° | 86° | – / – | 72° |
| Nov 1 | 85° | 86° | – / – | 72° |
| Nov 2 | 85° | 86° | – / – | 72° |
| Nov 3 | 84° | 85° | 90° / 73° | 72° |
| Nov 4 (forecast) | 81° | 83° | 83° / 68° | 72° |
| Nov 5 (forecast) | 81° | 83° | 89° / 71° | 72° |
| Nov 6 (forecast) | 79° | 81° | 82° / 66° | 72° |
| Nov 7 (forecast) | 76° | 79° | 80° / 63° | 72° |
| Nov 8 (forecast) | 73° | 76° | 74° / 57° | 72° |
| Nov 9 (forecast) | 71° | 74° | 75° / 58° | 72° |
| Nov 10 (forecast) | 70° | 73° | 78° / 61° | 71° |
Which grass grows in Harlingen
With mild winters (January averages 61°F), most Harlingen lawns are warm-season grasses such as bermudagrass, St. Augustine, zoysia and centipede. They grow through summer and slow or go dormant in winter.
Harlingen 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 | 60° | 61° | 61° |
| Feb | 63° | 64° | 65° |
| Mar | 70° | 71° | 70° |
| Apr | 76° | 78° | 76° |
| May | 82° | 84° | 81° |
| Jun | 86° | 88° | 85° |
| Jul | 87° | 89° | 86° |
| Aug | 88° | 90° | 86° |
| Sep | 84° | 86° | 82° |
| Oct | 78° | 80° | 77° |
| Nov | 69° | 70° | 68° |
| Dec | 63° | 64° | 62° |
Soil: average of our daily estimates, 2005–2025. Air: NOAA 1991–2020 normals for the station.
Typical lawn dates in Harlingen
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) (in 11 of 21 years) | Feb 11 | Jan 27 |
| Crabgrass model: 250 growing degree days | Jan 9 | Jan 7 |
| Pre-emergent window opens (2-inch soil 50°F) | early Feb | Feb 1 |
| Crabgrass begins to sprout (2-inch soil 55°F) | Feb 15 | Feb 15 |
| Cool-season lawns start growing (4-inch soil 55°F) | Feb 1 | Feb 3 |
| Warm-season seeding opens (4-inch soil 65°F) | Feb 11 | Feb 14 |
| Cool-season seeding opens (4-inch soil under 70°F) | Nov 20 | not yet |
Checked against a real sensor
Measured nearby: 82°F at 2 inches on Nov 3, at the USDA SCAN site “Weslaco”, 16 miles away.
Our estimate for Harlingen on Nov 3 is 84°F; the sensor read 83°F at 4 inches against our 85°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 KHRL (HARLINGEN RIO GRANDE VALLEY INTL AP), daily data since 1952. Forecast: National Weather Service, BRO office, issued Nov 4, 2026, 7:00 AM EST. Last observed day: Nov 3, 2026.
Harlingen questions
What is the soil temperature in Harlingen today? Our estimate for Nov 3 is 84°F at 2 inches and 85°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 Harlingen? Soil here rarely cools below 55°F, so there is no clean spring window; frost-free areas usually apply in late winter by calendar date.
When can I seed bermudagrass in Harlingen? Seed or sod now. 4-inch soil is 85°. Seed planted later than late summer has little warm weather left to establish before dormancy.
Is it too late to fertilize in Harlingen? Rarely goes dormant. Soil stays warm enough here that warm-season grass slows in winter rather than going fully dormant.
When is the last frost in Harlingen? The last 32°F night of spring has typically come around Feb 11, and as late as Feb 20 in 1 year in 10. The first fall freeze typically arrives around Dec 10.
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.