San Francisco frost dates and planting season

Name: San Francisco
Address: California, United States

When to plant vegetables here. Cover calendars (fleece, cold frame, unheated greenhouse) are on each plant’s when-to-plant page.

San Francisco is frost-free here (frost in fewer than about 1 winter in 10). Growing windows follow temperature limits, not frost dates. Cool-season crops can be planted any time of year here. Wait until about May 4 for warm-season crops.

Frost-free days365all year (frost-free)

Cover calendars (fleece, cold frame, unheated greenhouse) live on each crop’s when-to-plant page.

Weekly possible temperature33 – 96 °F

Frost-free daysall year (frost-free)

Days suitable for warm-season vegetables189 (May 4 – November 8)

Days suitable for cool-season vegetables365 (January 1 – December 31)

Calculated by Plan & Plant · Method · Data 2019–2026

Frost and suitability dates are typical figures from climate statistics. Microclimates vary; they are not a guarantee.

Frost dates calculated by Plan & Plant from Weather data by Open-Meteo.com (CC BY 4.0). Local frost pockets, valleys and coastal sites can differ by 1–3 weeks.

How we calculated this

Data: ERA5-Land via Open-Meteo, cell 37.77, -122.42, years 2019–2026 (not a 30-year climate normal yet).
Typical and safer dates: Typical last frost is the date after which half of winters in this sample had no more frost; safer is later in the sample so fewer winters still frosted.
Confidence: Provisional — short or thin sample for this place.
Full methodology (algorithm 2026-10-season-6).

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What to plant when

Cool-season vegetables

Outdoor start: any time of year

Suitable window: January 1 – December 31

Cool-season crops prefer cooler weather.

See cool-season details

Warm-season vegetables

Earliest outdoor start: May 4

Suitable window: May 4 – November 8

Warm-season crops need mild or warm weather and cannot take frost.

Frost kills these crops, and cold snaps set them back.

See warm-season details

Green = usually good weeks to grow; blue or gray = usually too cold for that crop type.

Starter plants for San Francisco

Cool-season

Radish Sow: January 1 – December 31 Planting dates
Arugula Sow: January 1 – December 31 Planting dates
Spinach Sow: January 1 – December 31 Planting dates
Lettuce Sow: January 1 – December 31 Planting dates
Kale Sow: January 1 – February 25 Planting dates
Beet Sow: January 1 – December 31 Planting dates

Warm-season

Zucchini Sow: May 20 – July 14 Planting dates
Cucumber Sow: May 20 – July 14 Planting dates
Green bean Sow: April 12 – November 8 Planting dates
Tomato Transplant: April 17 – June 11 Start indoors, then transplant. Planting dates
Bell pepper Transplant: May 20 – July 14 Start indoors, then transplant. Planting dates

How these dates are judged

Last frost: The typical last spring date when frost is still expected.
First frost: The typical first fall date when frost returns.
Frost-free days: The approximate days between those two dates.
Cool-season vegetables: Crops that prefer cooler weather, such as lettuce, kale, peas, and radish.
Warm-season vegetables: Crops that need warm weather and cannot take frost, such as tomato, pepper, squash, and beans.

Cool-season planting window

All year (365 days)

Warm-season planting window

May 4 – Nov 8 (189 days)

Weekly temperatures and planting windows

Temperatures across the year for San Francisco, with cool- and warm-season weeks and frost dates.

Possible min to max
Average min to max
Suitable
Tolerable
Too cold
Too hot

Selected week · tap a week or use the arrows

Week 1 · Jan 1 – Jan 4

Average 44 to 56 °F · Possible 33 to 60 °F

Cool season: suitable

Warm season: too cold

A week is suitable for a crop type when its average low and high sit inside that type's range and its possible readings stay within the frost and heat limits (cool: 28 °F to 81 °F, warm: 32 °F to 90 °F); crossing a limit makes it tolerable, and for warm crops any chance of frost makes it too cold.

Based on average frost dates.

California, United States · 37.77, -122.42 · 2026

Coldest weekly possible temperature33 °F

Hottest weekly possible temperature96 °F

Last expected spring frost

First expected fall frost

Show all 53 weeks