Thunder Bay weather by month

Check out Thunder Bay weather averages by month. Compare detailed monthly climate statistics including temperature, rainfall and sunshine figures.

Temperature
Rainfall
Sunshine & UV index

Temperature in Thunder Bay (°C)

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Max temperature (daytime)	-9	-6	0	8	15	20	24	22	17	10	2	-6
Min temperature (night-time)	-21	-19	-12	-3	2	7	11	10	6	1	-7	-16
Heat & Humidity	0	0	0	0	0	0	0	0	0	0	0	0
Sea temperature	2	2	2	2	3	4	7	13	13	8	5	4

Note: 0 = None, L = Low, M = Moderate, H = High, VH = Very high, E = Extreme

Sunshine & UV index in Thunder Bay

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Daily hours of sunshine	4	5	5	7	8	9	10	8	5	4	3	3
Daily hours of daylight	9	10	12	14	15	16	16	14	13	11	9	8
UV Index (Maximum)	1	1	3	4	6	7	7	6	5	2	1	1

Rainfall in Thunder Bay

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Number of days with some rain	11	9	10	9	11	13	12	13	13	11	10	11
Average monthly rainfall (mm)	38	27	42	45	70	82	82	88	88	60	49	45

More about Thunder Bay

Thunder Bay by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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The climate guide for Ontario (Thunder Bay) shows long term monthly weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

What's the climate like in Thunder Bay?

Thunder Bay has a cold climate with warm summers and some rainfall in all months.

Thunder Bay weather in January

Expect daytime maximum temperatures of -9°C in Thunder Bay, Ontario in January based on long-term weather averages. There are 4 hours of sunshine per day on average with 11 days with some rainfall, which might fall as snow.

-9
-9°C max day temperature
4
4 hours of sunshine per day
11
11 days with some rainfall
-21
-21°C min night temperature
9
9 hours of daylight per day
0
No heat & humidity
38
38 mm of monthly rainfall
1
1 (Low) UV index
2
2°C sea temperature

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Thunder Bay weather in February

Expect daytime maximum temperatures of -6°C in Thunder Bay, Ontario in February based on long-term weather averages. There are 5 hours of sunshine per day on average, which might fall as snow.

-6
-6°C max day temperature
5
5 hours of sunshine per day
9
9 days with some rainfall
-19
-19°C min night temperature
10
10 hours of daylight per day
0
No heat & humidity
27
27 mm of monthly rainfall
1
1 (Low) UV index
2
2°C sea temperature

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Thunder Bay weather in March

Expect daytime maximum temperatures of 0°C in Thunder Bay, Ontario in March based on long-term weather averages. There are 5 hours of sunshine per day on average with 10 days with some rainfall and typically 42 mm of rainfall in the month, which might fall as snow.

0
0°C max day temperature
5
5 hours of sunshine per day
10
10 days with some rainfall
-12
-12°C min night temperature
12
12 hours of daylight per day
0
No heat & humidity
42
42 mm of monthly rainfall
3
3 (Moderate) UV index
2
2°C sea temperature

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Thunder Bay weather in April

Expect daytime maximum temperatures of 8°C in Thunder Bay, Ontario in April based on long-term weather averages. There are 7 hours of sunshine per day on average with typically 45 mm of rainfall in the month.

8
8°C max day temperature
7
7 hours of sunshine per day
9
9 days with some rainfall
-3
-3°C min night temperature
14
14 hours of daylight per day
0
No heat & humidity
45
45 mm of monthly rainfall
4
4 (Moderate) UV index
2
2°C sea temperature

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Thunder Bay weather in May

Expect daytime maximum temperatures of 15°C in Thunder Bay, Ontario in May based on long-term weather averages. There are 8 hours of sunshine per day on average with 11 days with some rainfall and typically 70 mm of rainfall in the month.

15
15°C max day temperature
8
8 hours of sunshine per day
11
11 days with some rainfall
2
2°C min night temperature
15
15 hours of daylight per day
0
No heat & humidity
70
70 mm of monthly rainfall
6
6 (High) UV index
3
3°C sea temperature

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Thunder Bay weather in June

Expect daytime maximum temperatures of 20°C in Thunder Bay, Ontario in June based on long-term weather averages. There are 9 hours of sunshine per day on average with 13 days with some rainfall and typically 82 mm of rainfall in the month.

20
20°C max day temperature
9
9 hours of sunshine per day
13
13 days with some rainfall
7
7°C min night temperature
16
16 hours of daylight per day
0
No heat & humidity
82
82 mm of monthly rainfall
7
7 (High) UV index
4
4°C sea temperature

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Thunder Bay weather in July

Expect daytime maximum temperatures of 24°C in Thunder Bay, Ontario in July based on long-term weather averages. There are 10 hours of sunshine per day on average with 12 days with some rainfall and typically 82 mm of rainfall in the month.

24
24°C max day temperature
10
10 hours of sunshine per day
12
12 days with some rainfall
11
11°C min night temperature
16
16 hours of daylight per day
0
No heat & humidity
82
82 mm of monthly rainfall
7
7 (High) UV index
7
7°C sea temperature

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Thunder Bay weather in August

Expect daytime maximum temperatures of 22°C in Thunder Bay, Ontario in August based on long-term weather averages. There are 8 hours of sunshine per day on average with 13 days with some rainfall and typically 88 mm of rainfall in the month.

22
22°C max day temperature
8
8 hours of sunshine per day
13
13 days with some rainfall
10
10°C min night temperature
14
14 hours of daylight per day
0
No heat & humidity
88
88 mm of monthly rainfall
6
6 (High) UV index
13
13°C sea temperature

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Thunder Bay weather in September

Expect daytime maximum temperatures of 17°C in Thunder Bay, Ontario in September based on long-term weather averages. There are 5 hours of sunshine per day on average with 13 days with some rainfall and typically 88 mm of rainfall in the month.

17
17°C max day temperature
5
5 hours of sunshine per day
13
13 days with some rainfall
6
6°C min night temperature
13
13 hours of daylight per day
0
No heat & humidity
88
88 mm of monthly rainfall
5
5 (Moderate) UV index
13
13°C sea temperature

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Thunder Bay weather in October

Expect daytime maximum temperatures of 10°C in Thunder Bay, Ontario in October based on long-term weather averages. There are 4 hours of sunshine per day on average with 11 days with some rainfall and typically 60 mm of rainfall in the month.

10
10°C max day temperature
4
4 hours of sunshine per day
11
11 days with some rainfall
1
1°C min night temperature
11
11 hours of daylight per day
0
No heat & humidity
60
60 mm of monthly rainfall
2
2 (Low) UV index
8
8°C sea temperature

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Thunder Bay weather in November

Expect daytime maximum temperatures of 2°C in Thunder Bay, Ontario in November based on long-term weather averages. There are 3 hours of sunshine per day on average with 10 days with some rainfall and typically 49 mm of rainfall in the month, which might fall as snow.

2
2°C max day temperature
3
3 hours of sunshine per day
10
10 days with some rainfall
-7
-7°C min night temperature
9
9 hours of daylight per day
0
No heat & humidity
49
49 mm of monthly rainfall
1
1 (Low) UV index
5
5°C sea temperature

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Thunder Bay weather in December

Expect daytime maximum temperatures of -6°C in Thunder Bay, Ontario in December based on long-term weather averages. There are 3 hours of sunshine per day on average with 11 days with some rainfall and typically 45 mm of rainfall in the month, which might fall as snow.

-6
-6°C max day temperature
3
3 hours of sunshine per day
11
11 days with some rainfall
-16
-16°C min night temperature
8
8 hours of daylight per day
0
No heat & humidity
45
45 mm of monthly rainfall
1
1 (Low) UV index
4
4°C sea temperature

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