Thunder Bay Snowfall Totals & Accumulation Averages
This page pulls together information on when, how much and how often Thunder Bay, Ontario has snow.
There are data and descriptions here of how many days it snows and the total amount of snowfall that Thunder Bay usually gets. There are also monthly and yearly counts of the days that Thunder Bay normally has heavy snowstorms and deep snow accumulated on the ground. Plus there's information on when the city can expect its first and last snowfalls of the season.
All the numbers are long-term historical averages based on weather data gathered from 1981 to 2010 at the Thunder Bay International Airport.
How Often it Snows in Thunder Bay
This first table lists monthly and yearly totals for amount of snow and how many days it snows at least 0.2 centimetres (0.08 inches).
| Days | Inches | Centimetres | |
|---|---|---|---|
| 12.9 | January | 14.4 | 36 |
| 9.6 | February | 8.3 | 21 |
| 8.4 | March | 7.2 | 18 |
| 4.0 | April | 4.0 | 10 |
| 0.5 | May | 0.4 | 1 |
| 0.3 | September | 0.4 | 1 |
| 3.4 | October | 3.7 | 9 |
| 9.7 | November | 10.4 | 26 |
| 13.9 | December | 15.3 | 39 |
| 62.5 | Year | 64.1 | 163 |
When Thunder Bay Has Its First & Last Snowfalls
The first snowfall of winter for Thunder Bay usually arrives in October, but can show up as early as September.
The season's last snowfall typically happens in April although in some years a late snow lands in May.
Thunder Bay is normally free of snow every year from June to August.
How Many Snowstorms Thunder Bay Gets
Most days of snowfall in Thunder Bay leave less than five centimetres (2 inches) of fresh snow on the ground. For ten days a year on average, the amount of new snow totals at least five cm.
Big snowstorms of over ten cm a day normally occur three or four times a year. But major blizzards that dump 25 cm or more in one day are rare events that happen just once a decade. Storms this severe are most likely to appear in January.
| 5 cm 2.0 inches |
10 cm 3.9 inches |
25 cm 9.8 inches | |
|---|---|---|---|
| January | 2.1 | 0.9 | 0.1 |
| February | 1.2 | 0.4 | 0.0 |
| March | 1.1 | 0.2 | 0.0 |
| April | 0.5 | 0.2 | 0.0 |
| May | 0.1 | 0.0 | 0.0 |
| September | 0.1 | 0.0 | 0.0 |
| October | 0.6 | 0.2 | 0.0 |
| November | 1.6 | 0.6 | 0.0 |
| December | 2.7 | 1.0 | 0.0 |
| Year | 9.9 | 3.5 | 0.1 |
How Much Snow Normally Accumulates in Thunder Bay
For about 127 days a year, Thunder Bay has at least a centimetre of snow on the ground. In mid-winter the snowpack averages around 29 cm deep.
| 1 cm 0.4 inches |
5 cm 2.0 inches |
10 cm 3.9 inches |
20 cm 7.9 inches | |
|---|---|---|---|---|
| 29.1 | 27.6 | January | 25.8 | 23.3 |
| 28.2 | 28.2 | February | 26.6 | 19.2 |
| 26.1 | 21.2 | March | 14.9 | 9.9 |
| 5.0 | 2.5 | April | 2.0 | 1.3 |
| 0.1 | 0.0 | May | 0.0 | 0.0 |
| 1.1 | 0.1 | October | 0.0 | 0.0 |
| 11.9 | 4.2 | November | 2.6 | 0.9 |
| 24.9 | 19.1 | December | 14.5 | 10.5 |
| 126.5 | 102.7 | Year | 86.4 | 65.0 |
Reference
Environment Canada. Meteorological Service of Canada. Canadian Climate Normals. 1981-2010 Climate Normals & Averages.