Forecast confidence: Medium· models disagree by 3°C
Thunder Bay weather
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Drizzle,cooler tomorrow
Env. Canada, the European and the American model put Thunder Bay's high today between 17° and 20°, a 3° split. Tomorrow: cloudy, around 12°, with a 1% chance of rain.
Thunder Bay swings 36°C across the year, from 21°C highs in July to -15°C lows in January, and June is usually the wettest month in a year that brings about 674 mm of precipitation. Over 10 years of recorded weather it averages 18 days a year at 25°C or above, 1 of them at 30°C or above, 169 frost nights, and rain on 109 days.
Warmest month
July
21°C average high
Coldest month
January
-15°C average low
Wettest month
June
674 mm a year
Comfortable
3 months
July, August and September
Residents
109,000
share this forecast
Most accurate here
European
85/100 CheckWeather Score
Warm days
18 days
a year at 25°C or above
Frost nights
169 nights
a year below 0°C
Rain days
109 days
a year with 1 mm or more
Day counts are from the ERA5 reanalysis for Thunder Bay’s grid square, 2016 to 2025, counted the same way for every city so the numbers compare. A reanalysis square is an area, not a weather station, so it is good for counting days and not for a single day’s record.
The weather map: all three models at once
Env. Canada, European, American side by side around Thunder Bay and nearby towns.Live rain radar →
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Thunder Bay hourly forecast: next 14 hours
consensus of the three models
Rain in the next 24 hours, model by model
each model's own hourly precipitation, side by side
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Thunder Bay 10-day forecast, out to 14 days
where the models agree, and where they split
Today
Drizzle
19°9°
±3°
Tomorrow
Cloudy
12°4°
±4°
Mon
Cloudy
7°1°
models agree
Tue
Drizzle
8°2°
models agree
Wed
Drizzle
13°8°
±4°
Thu
Cloudy
13°5°
±3°
Fri
Drizzle
10°4°
models agree
Sat
Light rain
13°7°
±3°
Sun
Heavy drizzle
13°8°
models agree
Mon
Light drizzle
10°3°
±4°
Tue
Light drizzle
6°2°
models agree
Wed
Light drizzle
8°0°
models agree
Thu
Mostly clear
8°2°
models agree
Fri
Partly cloudy
9°2°
±7°
Thunder Bay, Ontario is at its warmest in Jul (average highs near 21°C) and coldest in Jan (lows around -15°C), with roughly 674 mm of precipitation across the year. Below, compare what Env. Canada, European, American forecast for Thunder Bay right now, and see exactly where they disagree.
average daytime high and overnight low across a typical year (1991-2020)
Jan
-9°
-15°
Feb
-6°
-15°
Mar
-1°
-8°
Apr
7°
-1°
May
13°
4°
Jun
18°
9°
Jul
21°
13°
Aug
21°
13°
Sep
16°
8°
Oct
10°
3°
Nov
2°
-4°
Dec
-6°
-11°
Source: 1991-2020 averages, ERA5 for this place adjusted with NASA POWER.
How Thunder Bay's weather has changed since 1995
30 years of daily data, 1995-2024, shown as change
+0.8°C
Around Thunder Bay, the difference between 1995-2004 and 2015-2024 is +0.8°C, within the normal swing from year to year.
1995each stripe is one year2024
cooler than averagearound averagewarmer than average
Days above 25°C
10 more days a year
2015-2024 against 1995-2004. Within the normal year-to-year swing
Frost nights
8 fewer nights a year
2015-2024 against 1995-2004, below 0°C. Within the normal year-to-year swing
Average wind
no clear change
2015-2024 against 1995-2004. Within the normal year-to-year swing
Bars: each year against the area's 30-year average. Dashed lines: the average of the first and the last ten years.
See the numbers year by year
Year
Temp vs average
Days >25°C vs avg
Frost nights vs avg
Wind vs avg
1995
−0.6°C
+19
+9
+4%
1996
−2.4°C
−10
+17
+1%
1997
−1.0°C
−9
+17
−3%
1998
+1.9°C
+11
−16
+1%
1999
+0.5°C
−12
−1
+1%
2000
−0.5°C
−15
−0
+1%
2001
+0.3°C
−10
−4
−3%
2002
−0.4°C
+1
+27
−3%
2003
−0.6°C
−6
+10
+1%
2004
−0.9°C
−17
+7
+1%
2005
+0.2°C
+1
−0
−3%
2006
+1.4°C
+19
+1
+1%
2007
+0.3°C
+14
−14
+4%
2008
−1.1°C
−16
−5
+1%
2009
−0.8°C
−19
+4
−3%
2010
+1.3°C
+8
−23
+1%
2011
+0.1°C
+0
−3
−3%
2012
+1.8°C
+13
−8
−3%
2013
−1.4°C
−7
+10
+4%
2014
−2.3°C
−20
+1
+1%
2015
±0.0°C
−9
−12
+1%
2016
+1.0°C
+3
−5
−3%
2017
−0.1°C
−13
+3
+1%
2018
−0.5°C
+16
+12
−3%
2019
−1.0°C
−1
+7
+1%
2020
+0.4°C
+13
+17
+1%
2021
+1.9°C
+26
−10
+1%
2022
−0.9°C
−5
+4
+4%
2023
+1.0°C
+4
−6
+1%
2024
+2.3°C
+11
−24
+1%
Source: NASA POWER daily data from the MERRA-2 reanalysis, 1995-2024. Each value describes a grid square of about 50 km around Thunder Bay, not a weather station, and a square that takes in sea or a large lake runs milder than the city itself. That is why this section shows change against the square's own 30-year average rather than counts you could compare with a local station. Rain and snow are left out because their long-term record in this dataset is not consistent over time. "Within the normal year-to-year swing" means the change is smaller than the usual differences between single years.
Which forecast is most accurate in Thunder Bay?
CheckWeather Score, graded against the weather that actually happened
Provider
CheckWeather-score
Temp
Wind
Rain
Run by
European ★ Best
85
/100rank #1
85±0.8°C
97±1.7 km/h
7687% hit
ECMWF - European Centre for Medium-Range Weather ForecastsReading, United Kingdom
EC
Env. Canada
83
/100rank #2
72±1.6°C
94±2.8 km/h
8994% hit
Environment and Climate Change CanadaDorval, Québec, Canada
American
82
/100rank #3
75±1.4°C
94±2.9 km/h
8290% hit
NOAA / NCEP (United States)College Park, Maryland, USA
The accuracy above is the measured record. This is your opinion: which forecast service do you trust most in Canada? Give each 1 to 5 stars.
Env. CanadaGEM model
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EuropeanECMWF
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AmericanNOAA GFS
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One vote per service. Anonymous: we store no personal data, only a one-way hash of your connection for a day to stop double votes.
Where the models disagree
temperature and rain, judged separately
Day
Temperature
Rain
Today
±3°17° to 20°
±64%21% to 85% chance
Tomorrow
±4°10° to 13°
±1%0% to 1% chance
Mon
±2°6° to 8°
models agree0% to 0% chance
Tue
±2°7° to 9°
±27%42% to 69% chance
Wed
±4°11° to 15°
±19%51% to 70% chance
The models often agree on temperature and still split on rain, and rain is usually what decides whether a plan survives. A wide rain range means the shower is genuinely uncertain, not that the forecast is wrong.
Sunrise and sunset in Thunder Bay
today, local time
Sunrise
08:30
Sunset
18:50
Daylight
10h 20m
Common questions
What's the weather in Thunder Bay today?
Saturday, October 24: Env. Canada, the European and the American model put Thunder Bay's high today between 17° and 20°, a 3° split. Tomorrow: cloudy, around 12°, with a 1% chance of rain. The forecast on this page refreshes live.
Will it rain in Thunder Bay today or tomorrow?
Rain looks unlikely in Thunder Bay on Sunday, October 25: no model gives more than 1% (Env. Canada 0%, European 0%, American 1%). On Saturday, October 24 the highest chance of rain from any model is 85%. The hourly strip and the model-by-model rain panel above update live.
Which forecast is most accurate for Thunder Bay?
Over the last 30 days, the European model has been the most accurate for Thunder Bay (CheckWeather Score 85/100), ahead of the Env. Canada at 83. We grade every model against the recorded weather. See the CA accuracy scoreboard for the full method.
What is the warmest month in Thunder Bay?
July is typically the warmest month in Thunder Bay, with average highs around 21°C.
How cold does Thunder Bay get?
The coldest month in Thunder Bay is January, when overnight lows average about -15°C.
How much rain does Thunder Bay get?
Thunder Bay sees roughly 674 mm of precipitation a year, with June usually the wettest month.
Is Thunder Bay getting warmer?
Not clearly. In NASA's reanalysis for the area around Thunder Bay, the difference between 1995-2004 and 2015-2024 is 0.8°C, within the normal swing from year to year.
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