Frost Dates for Los Osos, CA 93402

Last spring frost January 24 · First fall frost December 29 · 339 frost-free days · USDA Zone 10a

Frost probability for 93402

Frost10%50%90%
Spring (last frost)March 29January 24—
Fall (first frost)November 21December 29—

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (16.2 km away); the 50% date is the median year.

Month by month in Los Osos

MonthWhat to do
JanuaryLast frost around January 24. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
FebruaryFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
MarchSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
AprilHarvest regularly to encourage production. Monitor for pests and disease.
MayMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
JuneDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
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 29). Transplant fall brassicas. Sow spinach, arugula, and radishes.
DecemberFirst frost around December 29. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.

What grows in a 339-day season

Frequently Asked Questions

What is the last frost date for Los Osos, CA (ZIP 93402)?

The median last spring frost date for Los Osos, CA (ZIP code 93402) is around January 24. 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 Los Osos, CA?

The median first fall frost date for Los Osos, CA is around December 29. 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 Los Osos, CA?

The frost-free growing season in Los Osos is about 339 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 Los Osos, CA?

Based on frost date patterns, Los Osos 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 Los Osos, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around January 24). For Los Osos, that's roughly November 29 to December 13. Transplant outdoors 1–2 weeks after your last frost.

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