What is the soil temperature in ZIP code 80503 today?

About 48°F on average in the top 4 inches (0–10 cm), low 44°F and high 52°F, from NOAA's GFS model run of Nov 11, 12:00 UTC (7 am Eastern). It is a model value for a grid cell 9.6 km from the ZIP centre, not a reading from your yard.

Is it time for crabgrass preventer in 80503?

The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from Mar 20 and 55°F from Mar 21.

ZIP 80503 · Longmont, CO · Nov 11, 2026

Soil temperature for ZIP code 80503

48°Faverage today, 0–4 in deep (modelled)
low 44°F · high 52°F

Modelled by NOAA GFS, not measured · run Nov 11, 12:00 UTC (7 am Eastern) · grid cell 9.6 km from the ZIP centre point

On a week ago

4° warmer

44°F on Nov 4

5-day mean

47°F

what the verdicts use

Held 55°F last spring

Mar 21

crabgrass germination temperature

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, modelled. Dots and line: daily average (dashed = forecast); bars: low to high; green band: 50–55°F.

View as table

Day	Average	Low	High
Nov 4	44.3°F	40.2°F	48.4°F	analysis
Nov 5	44.5°F	39.7°F	50.2°F	analysis
Nov 6	44.1°F	39.7°F	49.7°F	analysis
Nov 7	44.5°F	39.7°F	50.9°F	analysis
Nov 8	45.8°F	41.4°F	51.4°F	analysis
Nov 9	49.2°F	44.7°F	55.6°F	analysis
Nov 10	47.8°F	42.8°F	53.0°F	analysis
Today	48.0°F	44.2°F	52.2°F	analysis
Nov 12	48.0°F	43.6°F	53.7°F	forecast
Nov 13	47.1°F	43.5°F	50.7°F	forecast
Nov 14	44.1°F	40.4°F	47.9°F	forecast
Nov 15	43.2°F	38.9°F	48.1°F	forecast
Nov 16	42.1°F	37.5°F	47.1°F	forecast
Nov 17	42.1°F	37.2°F	48.2°F	forecast

Source: NOAA NCEP GFS 0.25°, 0–10 cm soil temperature, run Nov 11, 12:00 UTC (7 am Eastern).

Spring 2026 threshold dates

From the 5-day mean held for 10 days or more.

Soil	What it means	Held from (spring 2026)
40°F	Peas and lettuce	Feb 6
50°F	Pre-emergent window opens	Mar 20
55°F	Crabgrass can germinate	Mar 21
60°F	Tomatoes	Jun 2
65°F	Warm-season grass seed	Jun 17

Boulder, CO, 18 km away: the full city page, with the 2026 season chart, growing degree days and nearby cities →

Nearby ZIP codes

Today's modelled average.

80544 50°F · 80501 49°F · 80301 50°F · 80304 50°F · 80504 49°F · 80513 49°F · 80540 40°F · 80455 39°F

More: crabgrass timing in Colorado · every Colorado city · how accurate the model is.

Questions

What is the soil temperature in ZIP code 80503 today?: About 48°F on average in the top 4 inches (0–10 cm), low 44°F and high 52°F, from NOAA's GFS model run of Nov 11, 12:00 UTC (7 am Eastern). It is a model value for a grid cell 9.6 km from the ZIP centre, not a reading from your yard.
Is it time for crabgrass preventer in 80503?: The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from Mar 20 and 55°F from Mar 21.

Data: Global Forecast System (GFS) 0.25°, soil temperature 0–10 cm (TSOIL) (NOAA National Centers for Environmental Prediction (NCEP)); 2025 Gazetteer ZIP Code Tabulation Areas (ZCTA) and 2024 cartographic boundary state outlines (U.S. Census Bureau).