Last Frost Date Seattle: Frost Dates, Late Frost Risk & Growing Season
When is the last spring frost and the first autumn frost in Seattle? Frost dates from 30 years of data, the risk of late frost, frost-free days and planting dates.
The frost season in Seattle
- Last frost (average): March 1
- In 1 year out of 10 it still freezes on March 23.
- First frost: November 21
- Frost-free season: 264 days
- Frost after 15 May: in 0 % of years
Frost days per month in Seattle
- January: 5.4 · 3 °C
- February: 3.9 · 3 °C
- March: 1.1 · 5 °C
- April: 0.1 · 6 °C
- May: 0 · 9 °C
- June: 0 · 12 °C
- July: 0 · 14 °C
- August: 0 · 14 °C
- September: 0 · 12 °C
- October: 0.3 · 8 °C
- November: 2.3 · 5 °C
- December: 5.4 · 3 °C
- Matched to the average lows of a weather station 17 km away – accurate to about ±1–2 weeks.
- Daily minimum temperatures 2 m above ground over 30 years (1991–2020), NASA POWER; station data: Deutscher Wetterdienst (CC BY 4.0). Ground frost can form while the air at 2 m is still +2 to +3 °C.