Frost dates · USDA zone 9a
Frost dates for Seattle, WA
Seattle, WA sees its last 32 °F night of spring around March 13 and its first of fall around November 17 — a 247-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 | Feb 20 | Dec 6 |
| Median — 1 year in 2 | Mar 13 | Nov 17 |
| 1 year in 10 | Apr 1 | Nov 1 |
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: 247 days median, at least 222 in 9 years of 10, at least 278 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 Feb 18 and first of Dec 2.
Seattle planting calendar, 2027
Every row runs from the median last frost (Mar 13) and median first frost (Nov 17) 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) | Dec 19 | Feb 13 | Jun 3 | 110 from transplant |
| Mustard greensGarnet Giant (Brassica juncea) | Direct sow | Mar 13 | Apr 12 | 30 from sow |
| CilantroSlow Bolt (Coriandrum sativum) | Feb 27 | Feb 27 | Apr 13 | 45 from sow |
| Genovese BasilGenovese | Feb 13 | Mar 27 | May 26 | 60 from transplant |
| CayenneLong Slim Cayenne (Capsicum annuum) | Jan 16 | Mar 20 | Jun 3 | 75 from transplant |
| HabaneroOrange Habanero (Capsicum chinense) | Jan 2 | Mar 27 | Jun 30 | 95 from transplant |
| JalapeñoEarly Jalapeño (Capsicum annuum) | Jan 16 | Mar 20 | Jun 3 | 75 from transplant |
| Marconi Red PepperMarconi Red (Capsicum annuum) | Jan 16 | Mar 20 | Jun 8 | 80 from transplant |
| SerranoSerrano Tampiqueño (Capsicum annuum) | Jan 16 | Mar 20 | Jun 8 | 80 from transplant |
| Nantes CarrotScarlet Nantes | Feb 27 | Feb 27 | May 8 | 70 from sow |
| TomatilloToma Verde | Jan 30 | Mar 20 | May 29 | 70 from transplant |
| Roma TomatoRoma VF (determinate paste) | Jan 30 | Mar 20 | Jun 3 | 75 from transplant |
| San Marzano TomatoSan Marzano (indeterminate paste) | Jan 30 | Mar 20 | Jun 8 | 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 Seattle grow?
Each sauce, scheduled for a Seattle container garden: when the first seeds go in and when enough fruit has ripened for one batch.
Seattle frost questions
When is the last frost in Seattle, WA?
The median last 32 °F freeze at SEATTLE BOEING FLD, WA is March 13: half of years see a later one. One year in ten, a freeze still comes after April 1; nine years in ten, it comes after February 20. Source: NOAA NCEI 1991–2020 U.S. Climate Normals.
When is the first frost in Seattle, WA?
The median first 32 °F freeze of fall is November 17. One year in ten it arrives before November 1; nine years in ten, before December 6.
How long is the growing season in Seattle, WA?
247 days between the last spring and first fall 32 °F freeze in a median year. Nine years in ten the season runs at least 222 days; one year in ten, at least 278 days.
What growing zone is Seattle, WA?
USDA hardiness zone 9a, per the 2023 USDA Plant Hardiness Zone Map for ZIP 98121. 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 Seattle, WA?
Start Roma VF (determinate paste) seeds indoors around Jan 30 and transplant around Mar 20, 1 week after the median last frost. To cut the freeze risk to one year in ten, wait for Apr 1. First ripe fruit lands around Jun 3.
When should I plant peppers in Seattle, WA?
Sow jalapeño indoors on a heat mat around Jan 16; transplant no earlier than Mar 20, and wait past it until nights hold above 50 °F — that can run weeks later. First green pods around Jun 3.
Nearby in Washington
- Kirklandlast frost Mar 8
- Bellevuelast frost Mar 8
- Shorelinelast frost Mar 8
- Burienlast frost Mar 2
- Redmondlast frost Mar 8
- Rentonlast frost Mar 13
All Washington frost dates → · How frost-date math drives a sowing calendar →