Frost dates · USDA zone 9b
Frost dates for San Luis Obispo, CA
San Luis Obispo, CA sees its last 32 °F night of spring around January 16 and its first of fall around December 25 — a 349-day freeze-free season in a typical year.
Pick a sauce; the Plan Builder runs this station's dates and hands back the calendar, plant count and gear list.
Freeze odds, by date
| Odds | Last spring freeze after | First fall freeze before |
|---|---|---|
| 9 years in 10 | Dec 11 (prior winter) | Feb 12 (next year) |
| Median — 1 year in 2 | Jan 16 | Dec 25 |
| 1 year in 10 | Feb 26 | Nov 25 |
The top row is the risky edge: in 9 years of 10 a spring freeze still comes after it, so tender transplants set out then need cover. The bottom row is the cautious date — only 1 year in 10 freezes after it — and the one to plan uncovered tender transplants against. Freeze-free season: 349 days median, at least 304 in 9 years of 10, no freeze at all in 1 year of 10. NOAA ranks season length year by year, so it is not the gap between two rows above. A hard freeze (28 °F) has a median last date of Jan 9 and first of Jan 6 (next year).
San Luis Obispo planting calendar, 2027
Every row runs from the median last frost (Jan 16) and median first frost (Dec 25) above, using each cultivar's days to maturity. Same engine as the Plan Builder.
| Crop | Start indoors | Transplant / plant | First harvest | Days |
|---|---|---|---|---|
| Hardneck GarlicSiberian (porcelain hardneck) | — | Oct 15prior fall | Jun 12 | 240 from sow |
| Spanish OnionYellow Sweet Spanish (long-day) | Oct 24 | Dec 19 | Apr 8 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Jan 16 | Feb 15 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Jan 2 | Jan 2 | Feb 16 | 45 from sow |
| Genovese BasilGenovese | Dec 19 | Jan 30 | Mar 31 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Nov 21 | Jan 23 | Apr 8 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Nov 7 | Jan 30 | May 5 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Nov 21 | Jan 23 | Apr 8 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Nov 21 | Jan 23 | Apr 13 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Nov 21 | Jan 23 | Apr 13 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Jan 2 | Jan 2 | Mar 13 | 70 from sow |
| TomatilloToma Verde | Dec 5 | Jan 23 | Apr 3 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Dec 5 | Jan 23 | Apr 8 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Dec 5 | Jan 23 | Apr 13 | 80 from transplant |
Tight means first harvest lands within two weeks of the median first fall frost: start that crop indoors on time or cover it in fall.
What sauce can San Luis Obispo grow?
Each sauce, scheduled for a San Luis Obispo container garden: when the first seeds go in and when enough fruit has ripened for one batch.
San Luis Obispo frost questions
When is the last frost in San Luis Obispo, CA?
The median last 32 °F freeze at SAN LUIS OBISPO POLY, CA is January 16: half of years see a later one. One year in ten, a freeze still comes after February 26; nine years in ten, it comes after December 11 (prior winter). Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in San Luis Obispo, CA?
The median first 32 °F freeze of fall is December 25. One year in ten it arrives before November 25; nine years in ten, before February 12 (next year).
How long is the growing season in San Luis Obispo, CA?
349 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 304 days; one year in ten, no freeze at all.
What growing zone is San Luis Obispo, CA?
USDA hardiness zone 9b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 93410. A zone describes the coldest winter night, not when frost ends, so it is the wrong number for a planting calendar — the frost dates on this page are the right one.
When should I plant tomatoes in San Luis Obispo, CA?
Start Roma VF (determinate paste) seeds indoors around Dec 5 and transplant around Jan 23, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Feb 26. First ripe fruit lands around Apr 8.
When should I plant peppers in San Luis Obispo, CA?
Sow jalapeño indoors on a heat mat around Nov 21; transplant no earlier than Jan 23, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Apr 8.
Nearby in California
- Santa Marialast frost Feb 4
- Lompoclast frost Jan 20
- Santa Barbaralast frost Jan 13
- Delanolast frost Jan 31
- Bakersfieldlast frost Jan 31
- Hanfordlast frost Feb 7
All California frost dates → · How frost-date math drives a sowing calendar →