Climate
| Statistics | Units | Jan | Feb | Mar | Apr | May | Jun |
|---|---|---|---|---|---|---|---|
| Temperature Mean Value |
F C |
5 -15.0 |
9 -12.8 |
21.9 -5.6 |
36.9 2.7 |
48.2 9.0 |
57 13.9 |
| High Temperature Mean Value |
F C |
16 -8.9 |
20.8 -6.2 |
32.4 0.2 |
47.7 8.7 |
60.3 15.7 |
68.9 20.5 |
| Low Temperature Mean Value |
F C |
-6.3 -21.3 |
-3.1 -19.5 |
11.1 -11.6 |
26.1 -3.3 |
36 2.2 |
45 7.2 |
| Precipitation Mean Monthly Value |
Inches mm |
1.3 32.4 |
1 25.6 |
1.7 40.9 |
1.9 47.1 |
2.8 69.3 |
3.4 84.0 |
| Snowfall Mean Monthly Value |
Inches cm |
18 43.3 |
11.9 28.5 |
11.9 28.5 |
6.2 14.8 |
0.9 2.2 |
0 0.0 |
| Statistics | Units | Jul | Aug | Sep | Oct | Nov | Dec | Avg |
|---|---|---|---|---|---|---|---|---|
| Temperature Mean Value |
F C |
63.9 17.7 |
61.5 16.4 |
52.2 11.2 |
41.7 5.4 |
27.3 -2.6 |
11.7 -11.3 |
36.4 2.42 |
| High Temperature Mean Value |
F C |
75.9 24.4 |
73.2 22.9 |
63.1 17.3 |
51.4 10.8 |
35.6 2.0 |
21.2 -6.0 |
47.2 8.45 |
| Low Temperature Mean Value |
F C |
51.8 11.0 |
50 10.0 |
41.2 5.1 |
31.8 -0.1 |
18.7 -7.4 |
1.9 -16.7 |
25.3 -3.7 |
| Precipitation Mean Monthly Value |
Inches mm |
3.3 79.9 |
3.6 88.5 |
3.5 86.4 |
2.5 60.9 |
2 49.4 |
1.6 39.3 |
2.4 58.64 |
| Snowfall Mean Monthly Value |
Inches cm |
0 0.0 |
0 0.0 |
0.2 0.4 |
2 4.9 |
11 26.5 |
19.3 46.4 |
6.8 16.29 |
The climate in the Thunder Bay area is typical of a mid-latitude inland location with a Great Lake Moderating influence. The moderating effect of Lake Superior results in cooler summer temperatures and warmer winter temperatures for an area along the lakeshore extending inland as far as 16 km. The summer period in Thunder Bay is approximately 97 days in length extending from the beginning of June to the beginning of September (beginning of summer is defined as the day the maximum daily temperature rises above 65 ºF.). Fall lasts about 60 days and extends to November. The winter season lasts approximately 6 months extending from November through to May. The first day of winter is taken as the first day with snowfall one inch or more.
The winter months in Thunder Bay are characterized by relatively cold temperatures and a relatively high incidence of sunshine. Daylight hours in the winter time are as short as 8:39 (hrs). The winter climate is well-suited to active outdoor recreational pursuits like skiing, skating and snowmobiling.
The summer months are normally characterized by cool evenings and relatively high incidence of mean monthly days with fog as compared to other areas in Canada. Daylight hours in the summer are as long as 16:00 (hrs). The summer period is well-suited to active outdoor recreation pursuits like hiking, boating and outdoor games like tennis and golf.
The season for passive recreation activities like beaching and sunbathing is significantly shorter than other more southerly areas in Ontario. However, an important consideration is the fact that the Thunder Bay summer climate is sometimes considered more comfortable during the summer months than more southerly Ontario areas because of lower humidity and cool nights.
The spring and fall periods are characterized by relatively cool temperatures during the day and evening, and a greater occurrence of strong winds. The autumn colour is impressive in the Thunder Bay area.
