Last Frost Date Boston: Frost Dates, Late Frost Risk & Growing Season
When is the last spring frost and the first autumn frost in Boston? Frost dates from 30 years of data, the risk of late frost, frost-free days and planting dates.
The frost season in Boston
- Last frost (average): April 5
- In 1 year out of 10 it still freezes on April 15.
- First frost: November 8
- Frost-free season: 216 days
- Frost after 15 May: in 0 % of years
Frost days per month in Boston
- January: 24.1 · -5 °C
- February: 21.4 · -4 °C
- March: 15.1 · 0 °C
- April: 2 · 5 °C
- May: 0 · 10 °C
- June: 0 · 15 °C
- July: 0 · 19 °C
- August: 0 · 18 °C
- September: 0 · 15 °C
- October: 0.2 · 9 °C
- November: 7.1 · 3 °C
- December: 19.3 · -1 °C
- Matched to the average lows of a weather station 9 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.