Last frost date in Walnut, CA

Average last frost

January 8

Expect the last frost in Walnut around January 8. Frost after February 18 happens in only one year out of ten. The first fall frost usually arrives about December 28, which leaves 354 frost-free days. An early freeze before December 5 happens one year in ten.

Safe after (10% risk): Feb 18
Average first frost: Dec 28
Frost-free season: 354 days
Hard freeze (28°F) ends: rare

Next 6 nights in Walnut

No frost in the next 6 nights

National Weather Service forecast, updated Oct 22, 12:57 UTC

ThuOct 2254°
FriOct 2353°
SatOct 2456°
SunOct 2558°
MonOct 2658°
TueOct 2758°

Frost risk through the year at Pomona/fairplex, 6.0 miles from Walnut.

Planting calendar for Walnut

Windows count forward or back from the average frost dates above. Click a crop for dates across California.

Start indoorsPlant outSow outdoorsFall plantingAverage last and first frost

Warm-season crops

JanFebMarAprMayJunJulAugSepOctNovDec

TomatoesFeb 15–Mar 1

PumpkinsFeb 15–Mar 1

SunflowersFeb 15–Mar 8

CucumbersFeb 22–Mar 1

CornFeb 15–Mar 1

Sweet potatoesFeb 15–Mar 1

WatermelonFeb 15–Mar 1

Green beansFeb 15–Mar 8

ZucchiniFeb 15–Mar 1

OkraFeb 15–Mar 1

PeppersFeb 15–Mar 1

BasilFeb 15–Mar 1

Butternut squashFeb 15–Mar 1

CantaloupeFeb 15–Mar 1

EggplantFeb 15–Mar 1

Cool-season crops

JanFebMarAprMayJunJulAugSepOctNovDec

PotatoesDec 11–Dec 25

OnionsNov 27–Dec 18

CarrotsDec 18–Jan 22

LettuceDec 25–Jan 15

BroccoliDec 11–Dec 25

BeetsDec 11–Jan 22

PeasNov 27–Dec 11

CabbageDec 11–Dec 25

RadishesDec 4–Jan 15

Brussels sproutsDec 25–Jan 8

SpinachNov 27–Dec 18

CilantroDec 25–Jan 15

KaleDec 11–Dec 25

Collard greensDec 11–Dec 25

TurnipsDec 11–Dec 25

DillJan 8–Jan 22

CeleryJan 15–Jan 22

CauliflowerDec 25–Jan 8

LeeksDec 25–Jan 8

Swiss chardDec 25–Jan 22

ParsleyDec 25–Jan 15

Fall bulbs and garlic

JanFebMarAprMayJunJulAugSepOctNovDec

Tulip bulbsDec 15–Jan 15

GarlicOct 15–Nov 30

Daffodil bulbsOct 15–Nov 30

Perennials

JanFebMarAprMayJunJulAugSepOctNovDec

StrawberriesDec 11–Dec 25

AsparagusDec 11–Dec 25

Frost probabilities

Threshold	Spring, 90% chance later	Spring, 50%	Spring, 10%	Fall, 10% chance earlier	Fall, 50%	Fall, 90%
Light frost, 32°F	Dec 14	Jan 8	Feb 18	Dec 5	Dec 28	Feb 2

Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.

Where these numbers come from

NOAA station Pomona/fairplex (USC00047050) sits 6.0 miles from the center of Walnut at 999 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.

Questions

When is the last frost in Walnut, CA?

The average last frost date in Walnut is January 8, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after February 18.

When is the first frost in Walnut?

The first frost in fall usually comes around December 28. One year in ten it arrives before December 5.

How long is the growing season in Walnut?

About 354 days between the average last and first frost.

When should I plant tomatoes in Walnut?

Plant tomato seedlings outside from February 15 to March 1. Start seeds indoors six to eight weeks earlier.

Nearby in California

All 348 cities in California