What is the soil temperature in ZIP code 93409 today?

About 66°F on average in the top 4 inches (0–10 cm), low 62°F and high 72°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 9.5 km from the ZIP centre, not a reading from your yard.

Is it time for crabgrass preventer in 93409?

The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from Jan 13 and 55°F from Jan 16.

ZIP 93409 · San Luis Obispo, CA · Nov 11, 2026

Soil temperature for ZIP code 93409

66°Faverage today, 0–4 in deep (modelled)
low 62°F · high 72°F

Modelled by NOAA GFS, not measured · run Nov 11, 12:00 UTC (7 am Eastern) · grid cell 9.5 km from the ZIP centre point

On a week ago

6° warmer

60°F on Nov 4

5-day mean

65°F

what the verdicts use

Held 55°F last spring

Jan 16

crabgrass germination temperature

What the soil says today

Pre-emergentSeason over
Cool-season seedToo late in the season
Warm-season seedWarm enough
TomatoesSoil warm enough
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	60.2°F	57.2°F	65.0°F	analysis
Nov 5	61.8°F	59.3°F	66.1°F	analysis
Nov 6	61.3°F	57.9°F	66.9°F	analysis
Nov 7	63.1°F	58.9°F	69.5°F	analysis
Nov 8	64.5°F	60.3°F	71.6°F	analysis
Nov 9	65.8°F	62.0°F	72.0°F	analysis
Nov 10	66.4°F	62.5°F	72.8°F	analysis
Today	66.3°F	62.5°F	71.5°F	analysis
Nov 12	64.6°F	62.0°F	67.5°F	forecast
Nov 13	62.1°F	60.4°F	63.8°F	forecast
Nov 14	60.4°F	58.1°F	63.5°F	forecast
Nov 15	59.1°F	56.0°F	63.0°F	forecast
Nov 16	58.9°F	57.2°F	61.3°F	forecast
Nov 17	59.5°F	57.8°F	62.9°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	never below
50°F	Pre-emergent window opens	Jan 13
55°F	Crabgrass can germinate	Jan 16
60°F	Tomatoes	Mar 14
65°F	Warm-season grass seed	Mar 17

San Luis Obispo, CA, 6 km away: the full city page, with the 2026 season chart, growing degree days and nearby cities →

Nearby ZIP codes

Today's modelled average.

93408 66°F · 93407 66°F · 93410 66°F · 93405 66°F · 93401 65°F · 93442 63°F · 93402 66°F · 93422 63°F

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

Questions

What is the soil temperature in ZIP code 93409 today?: About 66°F on average in the top 4 inches (0–10 cm), low 62°F and high 72°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 9.5 km from the ZIP centre, not a reading from your yard.
Is it time for crabgrass preventer in 93409?: The spring window is closed. It opens again when the soil holds 50°F. Last spring the soil held 50°F from Jan 13 and 55°F from Jan 16.

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).