Frost Dates for Palo Alto, CA 94303

Last spring frost February 3 · First fall frost December 11 · 311 frost-free days · USDA Zone 10a

Frost probability for 94303

Frost10%50%90%
Spring (last frost)February 28February 3December 20
Fall (first frost)November 18December 11January 15

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (2.0 km away); the 50% date is the median year.

Frost dates by ZIP code in Palo Alto, CA

ZIPLast spring frost (50%)First fall frost (50%)Zone
94303February 3December 1110a
94306February 3December 119b
94301February 3December 119b
94304February 3December 119b

Month by month in Palo Alto

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 3. 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 11). Transplant fall brassicas. Sow spinach, arugula, and radishes.
DecemberFirst frost around December 11. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.

What grows in a 311-day season

Frequently Asked Questions

What is the last frost date for Palo Alto, CA (ZIP 94303)?

The median last spring frost date for Palo Alto, CA (ZIP code 94303) is around February 3. 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 Palo Alto, CA?

The median first fall frost date for Palo Alto, CA is around December 11. 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 Palo Alto, CA?

The frost-free growing season in Palo Alto is about 311 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 Palo Alto, CA?

Based on frost date patterns, Palo Alto falls approximately in 10a. 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 Palo Alto, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around February 3). For Palo Alto, that's roughly December 9 to December 23. Transplant outdoors 1–2 weeks after your last frost.

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