Thunder Bay weather in September
Mild and comfortable, with some rainy days. Average highs of 18°C and lows of 11°C, with around 11 rainy days expected throughout the month.
While September isn't our top-rated month for Thunder Bay, it has its own appeal — typically lower prices, fewer crowds, and a more local feel.
Average high
18°C
Average low
11°C
Rainy days
11 days
Best months to visit
Year-round
What to do in Thunder Bay in September
Whatever the weather, Thunder Bay rewards curious visitors. Here are some of the best ways to spend your time:
Climb the Sleeping Giant overlooking the harbor
Kayak or paddleboard Lake Superior's calm bays
Fish for trout in nearby streams and lakes
Visit the Thunder Bay National Marine Conservation Area
Hike trails with dramatic lake and mountain views
Explore the historic waterfront and port infrastructure
What to pack for September
Layer up — a mid-weight jacket, jumpers, and comfortable trousers. Waterproof shoes are recommended. Scarves and gloves may be useful in the evenings.
Browse other months
January
-8C
Cold, with occasional showers.
February
-8C
Cold, with occasional showers.
March
-1C
Cold, with occasional showers.
April
5C
Cold, with some rainy days.
May
12C
Cool, with some rainy days.
June
18C
Mild and comfortable, with some rainy days.
July
22C
Mild and comfortable, with some rainy days.
August
21C
Mild and comfortable, with some rainy days.
September (you are here)
18C
Mild and comfortable, with some rainy days.
October
10C
Cool, with occasional showers.
November
3C
Cold, with occasional showers.
December
-3C
Cold, with occasional showers.
Book your September trip to Thunder Bay
Find hotels, tours and experiences for the perfect escape.
