Thunder Bay in Fall
In fall (September, October and November), Thunder Bay sees average daytime highs around 9°C and overnight lows near 2°C, with 206 mm of precipitation over about 29 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 20°C in early September to -2°C by late November. The sky is clear or mostly clear about 17% of the time across fall, and the air most often feels dry.
Fall is Thunder Bay's 2nd-best season to visit on our travel score. For the whole year in context, see Thunder Bay's year-round climate.
- Avg daytime high
- 9°C
- 2nd-warmest season
- Avg overnight low
- 2°C
- Precipitation
- 206 mm
- 29 wet days
- Avg wind
- 14 km/h
- Travel score
- 2.3
- 2nd-best season
- Months
- Sep · Oct · Nov
Temperature in Thunder Bay in Fall
Over the season highs ease from about 20°C in early September to -2°C by late November.
A typical fall day in Thunder Bay reaches about 9°C and drops to 2°C overnight. The warmest of the three months is September, the coolest November.
How fall really feels in Thunder Bay
Once humidity and wind are folded in, fall brings about 0 days that feel above 32°C and 50 that feel at or below 0°C.
The story in fall is cold — wind chill drags the overnight "feels like" below the raw low.
Thunder Bay weather by month
How the three fall months (September, October and November) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | -10° / -18° | 29 | 6.5 | 7.5 | 8.6 | 0.0 |
| Feb | -7° / -16° | 22 | 4.9 | 5.4 | 9.9 | 0.0 |
| Mar | -1° / -10° | 31 | 6.8 | 5.6 | 11.6 | 0.0 |
| Apr | 6° / -3° | 54 | 8.3 | 5 | 13.4 | 0.7 |
| May | 13° / 4° | 66 | 10.1 | 0.8 | 15 | 3.5 |
| Jun | 19° / 10° | 65 | 10.5 | 0 | 15.8 | 5.8 |
| Jul | 22° / 14° | 76 | 10.6 | 0 | 15.5 | 6.6 |
| Aug | 22° / 13° | 67 | 9.1 | 0 | 14.1 | 6.7 |
| Sep | 17° / 9° | 84 | 10.5 | 0 | 12.4 | 5.2 |
| Oct | 9° / 3° | 72 | 10.4 | 1.3 | 10.6 | 1.7 |
| Nov | 1° / -5° | 49 | 7.8 | 5.7 | 9 | 0.0 |
| Dec | -6° / -13° | 38 | 7.3 | 7.8 | 8.2 | 0.0 |
Cloud cover in Fall
The sky is clear or mostly clear about 17% of the time across fall.
Chance of precipitation in Fall
Thunder Bay gets around 206 mm of rain and snow over 29 wet days across fall. The line is the day-by-day chance of measurable precipitation.
Humidity in Fall
Most of fall feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Fall
Winds average 14 km/h across fall.
Sunrise & sunset in Fall
Daylight runs from about 13 h 12 min in early September to 8 h 24 min by late November. The lit band spans sunrise to sunset each day.
Solar energy in Fall
Average shortwave solar energy reaching the ground each day across fall, about 2.4 kWh/m².
Is fall a good time to visit Thunder Bay?
Our two travel scores rate fall for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
fall is a weaker month for outdoor sightseeing in Thunder Bay.
What to pack for Thunder Bay in Fall
From fall's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In fall, Thunder Bay sees daytime highs around 9°C and nights near 2°C. Pack a warm layer and a heavy coat. Worth having: rain gear. About 29 days see rain.
Sea temperature near Thunder Bay in Fall
The nearest coast averages about 10°C across fall — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in August at about 15°C and coldest in March near 1°C.
The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 2 | 1 | 1 | 2 | 3 | 4 | 9 | 15 | 14 | 10 | 6 | 4 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 2 | Bracing |
| Feb | 1 | Bracing |
| Mar | 1 | Bracing |
| Apr | 2 | Bracing |
| May | 3 | Bracing |
| Jun | 4 | Bracing |
| Jul | 9 | Bracing |
| Aug | 15 | Cool |
| Sep | 14 | Bracing |
| Oct | 10 | Bracing |
| Nov | 6 | Bracing |
| Dec | 4 | Bracing |
UV index in Thunder Bay in Fall
Clear-sky midday UV across fall averages around 3. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Thunder Bay peaks around June 17 at about 8 (very high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near December 21 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 6 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 2 | 3 | 5 | 6 | 8 | 6 | 6 | 5 | 3 | 1 | 1 |
| Level | Low | Low | Moderate | Moderate | High | Very high | High | High | Moderate | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 2 | Low |
| Mar | 3 | Moderate |
| Apr | 5 | Moderate |
| May | 6 | High |
| Jun | 8 | Very high |
| Jul | 6 | High |
| Aug | 6 | High |
| Sep | 5 | Moderate |
| Oct | 3 | Moderate |
| Nov | 1 | Low |
| Dec | 1 | Low |
Where is Thunder Bay?
Thunder Bay sits at 48.4°N, 89.3°W, 188 m above sea level, in Canada. The nearest listed city is Marquette, 247 km away.
Topography around Thunder Bay
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Thunder Bay.
Within 3 km, the terrain around Thunder Bay has only modest variations in elevation — a maximum elevation change of 20 m around an average of 188 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 297 m; within 80 km, significant variations in elevation — a maximum elevation change of 503 m.
The land around Thunder Bay is covered by artificial surfaces (41%) and trees (26%) within 3 km, trees (43%) and water (39%) within 16 km, and trees (57%) and water (40%) within 80 km.
Canada travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type A / B
- 120 V · 60 Hz
- Prices
- ≈ 83% of US
- price level, 2025
- GDP per capita
- $55,698
- 2025
- Happiness
- 6.7 / 10
- World Happiness, 2025
- Safe drinking water
- 97%
- of population, 2024
- Homicide rate
- 2
- per 100k, 2023
- Road deaths
- 5.3
- per 100k/yr, 2019
- Income group
- High
- World Bank
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Thunder Bay (48.382°, -89.2502°, elevation 188 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.