Frost Dates for Clayton, CA 94517

Last spring frost February 27 · First fall frost December 1 · 277 frost-free days · USDA Zone 9b

Frost probability for 94517

Frost10%50%90%
Spring (last frost)April 7February 27January 22
Fall (first frost)November 9December 1December 23

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (26.1 km away); the 50% date is the median year.

Month by month in Clayton

MonthWhat to do
JanuaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
FebruaryLast frost around February 27. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MarchFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
AprilSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
MayHarvest regularly to encourage production. Monitor for pests and disease.
JuneMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
JulyDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
NovemberFirst fall frost approaching (around December 1). Transplant fall brassicas. Sow spinach, arugula, and radishes.
DecemberFirst frost around December 1. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.

What grows in a 277-day season

Frequently Asked Questions

What is the last frost date for Clayton, CA (ZIP 94517)?

The median last spring frost date for Clayton, CA (ZIP code 94517) is around February 27. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Clayton, CA?

The median first fall frost date for Clayton, CA is around December 1. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Clayton, CA?

The frost-free growing season in Clayton is about 277 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Clayton, CA?

Based on frost date patterns, Clayton falls approximately in 9b. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Clayton, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around February 27). For Clayton, that's roughly January 2 to January 16. Transplant outdoors 1–2 weeks after your last frost.

Nearby and related