Frost dates · USDA zone 9b
Frost dates for Palo Alto, CA
Palo Alto, CA sees its last 32 °F night of spring around February 1 and its first of fall around December 7 — a 310-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 28 (prior winter) | Jan 6 (next year) |
| Median — 1 year in 2 | Feb 1 | Dec 7 |
| 1 year in 10 | Mar 4 | Nov 20 |
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: 310 days median, at least 272 in 9 years of 10, at least 347 days 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 4 and first of Dec 22.
Palo Alto planting calendar, 2027
Every row runs from the median last frost (Feb 1) and median first frost (Dec 7) 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) | Nov 9 | Jan 4 | Apr 24 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Feb 1 | Mar 3 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Jan 18 | Jan 18 | Mar 4 | 45 from sow |
| Genovese BasilGenovese | Jan 4 | Feb 15 | Apr 16 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Dec 7 | Feb 8 | Apr 24 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Nov 23 | Feb 15 | May 21 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Dec 7 | Feb 8 | Apr 24 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Dec 7 | Feb 8 | Apr 29 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Dec 7 | Feb 8 | Apr 29 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Jan 18 | Jan 18 | Mar 29 | 70 from sow |
| TomatilloToma Verde | Dec 21 | Feb 8 | Apr 19 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Dec 21 | Feb 8 | Apr 24 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Dec 21 | Feb 8 | Apr 29 | 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 Palo Alto grow?
Each sauce, scheduled for a Palo Alto container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Palo Alto frost questions
When is the last frost in Palo Alto, CA?
The median last 32 °F freeze at PALO ALTO, CA is February 1: half of years see a later one. One year in ten, a freeze still comes after March 4; nine years in ten, it comes after December 28 (prior winter). Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Palo Alto, CA?
The median first 32 °F freeze of fall is December 7. One year in ten it arrives before November 20; nine years in ten, before January 6 (next year).
How long is the growing season in Palo Alto, CA?
310 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 272 days; one year in ten, at least 347 days.
What growing zone is Palo Alto, CA?
USDA hardiness zone 9b, per the 2023 USDA Plant Hardiness Zone Map for ZIP 94304. 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 Palo Alto, CA?
Start Roma VF (determinate paste) seeds indoors around Dec 21 and transplant around Feb 8, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Mar 4. First ripe fruit lands around Apr 24.
When should I plant peppers in Palo Alto, CA?
Sow jalapeño indoors on a heat mat around Dec 7; transplant no earlier than Feb 8, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Apr 24.
Nearby in California
- Mountain Viewlast frost Jan 6
- Sunnyvalelast frost Jan 6
- Cupertinolast frost Mar 21
- Redwood Citylast frost Jan 17
- Newarklast frost Jan 1
- Santa Claralast frost Jan 12
All California frost dates → · How frost-date math drives a sowing calendar →