Frost Dates for Simi Valley, CA 93065

Last spring frost January 22 · First fall frost November 29 · 311 frost-free days · USDA Zone 10a

Frost probability for 93065

Frost10%50%90%
Spring (last frost)March 9January 22February 2
Fall (first frost)November 7November 29January 20

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (33.7 km away); the 50% date is the median year.

Frost dates by ZIP code in Simi Valley, CA

ZIPLast spring frost (50%)First fall frost (50%)Zone
93065January 22November 2910a
93063——10a

Month by month in Simi Valley

MonthWhat to do
JanuaryLast frost around January 22. 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.
OctoberFirst fall frost approaching (around November 29). Transplant fall brassicas. Sow spinach, arugula, and radishes.
NovemberFirst frost around November 29. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
DecemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.

What grows in a 311-day season

Frequently Asked Questions

What is the last frost date for Simi Valley, CA (ZIP 93065)?

The median last spring frost date for Simi Valley, CA (ZIP code 93065) is around January 22. 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 Simi Valley, CA?

The median first fall frost date for Simi Valley, CA is around November 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 Simi Valley, CA?

The frost-free growing season in Simi Valley 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 Simi Valley, CA?

Based on frost date patterns, Simi Valley 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 Simi Valley, CA?

Start tomato seeds indoors 6–8 weeks before your last frost date (around January 22). For Simi Valley, that's roughly November 27 to December 11. Transplant outdoors 1–2 weeks after your last frost.

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