Last frost date in SeaTac, WA
The average last frost in SeaTac is March 2. By March 23 the chance of another 32°F night drops to 1 in 10. The first fall frost usually arrives about November 23, which leaves 266 frost-free days. An early freeze before November 6 happens one year in ten.
- Safe after (10% risk)
- Mar 23
- Average first frost
- Nov 23
- Frost-free season
- 266 days
- Hard freeze (28°F) ends
- Feb 4
No frost in the next 6 nights
National Weather Service forecast, updated Oct 22, 12:57 UTC
- ThuOct 2244°
- FriOct 2339°
- SatOct 2442°
- SunOct 2543°
- MonOct 2643°
- TueOct 2743°
Planting calendar for SeaTac
Windows count forward or back from the average frost dates above. Click a crop for dates across Washington.
TomatoesMar 9–Mar 23
PumpkinsMar 16–Mar 30
SunflowersMar 2–Mar 23
CucumbersMar 16–Mar 23
CornMar 9–Mar 23
Sweet potatoesMar 23–Apr 6
WatermelonMar 16–Mar 30
Green beansMar 9–Mar 30
ZucchiniMar 9–Mar 23
OkraMar 23–Apr 6
PeppersMar 16–Mar 30
BasilMar 9–Mar 23
Butternut squashMar 9–Mar 23
CantaloupeMar 16–Mar 30
EggplantMar 16–Mar 30
PotatoesFeb 2–Feb 16
OnionsJan 19–Feb 9
CarrotsFeb 9–Mar 16
LettuceFeb 16–Mar 9
BroccoliFeb 2–Feb 16
BeetsFeb 2–Mar 16
PeasJan 19–Feb 2
CabbageFeb 2–Feb 16
RadishesJan 26–Mar 9
Brussels sproutsFeb 16–Mar 2
SpinachJan 19–Feb 9
CilantroFeb 16–Mar 9
KaleFeb 2–Feb 16
Collard greensFeb 2–Feb 16
TurnipsFeb 2–Feb 16
DillMar 2–Mar 16
CeleryMar 9–Mar 16
CauliflowerFeb 16–Mar 2
LeeksFeb 16–Mar 2
Swiss chardFeb 16–Mar 16
ParsleyFeb 16–Mar 9
Tulip bulbsNov 9–Dec 14
GarlicOct 15–Nov 30
Daffodil bulbsOct 15–Nov 30
StrawberriesFeb 2–Feb 16
AsparagusFeb 2–Feb 16Frost probabilities
| Threshold | Spring, 90% chance later | Spring, 50% | Spring, 10% | Fall, 10% chance earlier | Fall, 50% | Fall, 90% |
|---|---|---|---|---|---|---|
| Light frost, 32°F | Feb 5 | Mar 2 | Mar 23 | Nov 6 | Nov 23 | Dec 15 |
| Hard freeze, 28°F | Dec 20 | Feb 4 | Feb 28 | Nov 17 | Dec 10 | Jan 16 |
Read the spring 10% column as the date after which only one year in ten still gets frost. That is the safer date for tomatoes, peppers and basil.
Where these numbers come from
NOAA station Seattle Tacoma International Airport (USW00024233) sits 0.7 miles from the center of SeaTac at 370 feet. Its averages cover 1991 to 2020. Low spots, valleys and open fields can keep getting frost a week or two after the station stops; city centers and lakeshores usually get less of it.
Questions
When is the last frost in SeaTac, WA?
The average last frost date in SeaTac is March 2, based on NOAA 1991–2020 climate normals. There is a 10% chance of frost after March 23.
When is the first frost in SeaTac?
The first frost in fall usually comes around November 23. One year in ten it arrives before November 6.
How long is the growing season in SeaTac?
About 266 days between the average last and first frost.
When should I plant tomatoes in SeaTac?
Plant tomato seedlings outside from March 9 to March 23. Start seeds indoors six to eight weeks earlier.
Nearby in Washington
- TukwilaMar 2
- BurienMar 2
- Des MoinesMar 2
- KentMar 20
- RentonMar 13
- Mercer IslandMar 13
- Federal WayMar 8
- AuburnMar 20
- CovingtonApr 20
- SeattleMar 8
- BellevueMar 8
- Maple ValleyApr 20