Last Frost Date Thunder Bay: Frost Dates, Late Frost Risk & Growing Season
When is the last spring frost and the first autumn frost in Thunder Bay? Frost dates from 30 years of data, the risk of late frost, frost-free days and planting dates.
The frost season in Thunder Bay
- Last frost (average): May 17
- In 1 year out of 10 it still freezes on May 25.
- First frost: October 4
- Frost-free season: 142 days
- Frost after 15 May: in 57 % of years
Frost days per month in Thunder Bay
- January: 31 · -19 °C
- February: 28.1 · -17 °C
- March: 29.7 · -10 °C
- April: 24.1 · -3 °C
- May: 5.8 · 3 °C
- June: 0 · 9 °C
- July: 0 · 12 °C
- August: 0 · 12 °C
- September: 0.6 · 8 °C
- October: 12.3 · 1 °C
- November: 25.8 · -6 °C
- December: 30.9 · -14 °C
- No weather station nearby: plain grid values, which are often a little too cold – dates may therefore be late.
- 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.