A warm and muggy Thursday morning has settled over Thunder Bay, with mist and local smoke limiting visibility early in the day. The city is in for a hot, humid stretch with a few interruptions from scattered showers and thunderstorms. With a humidex approaching 40, today will feel particularly oppressive—take precautions if you’re spending time outdoors.
Today’s Weather Overview
Current Conditions
As of 8:00 AM EDT at Thunder Bay Airport:
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Temperature: 19.1°C
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Humidity: 97%
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Dew Point: 18.6°C
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Wind: Calm
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Visibility: 8 km due to mist and local smoke
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Barometric Pressure: 101.8 kPa, rising
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Conditions: Very humid, misty, and smoky
The forecast calls for a mix of sun and cloud today, with a 40% chance of showers both early this morning and again late this afternoon. There’s also a risk of a thunderstorm during those windows. Winds will shift south at 20 km/h by the afternoon.
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High: 29°C
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Humidex: 37°C – extremely muggy and potentially dangerous heat
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UV Index: 7 or high
Tonight
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Partly cloudy with a 40% chance of showers this evening, along with a continued risk of thunderstorms
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Winds shift from southwest to east, peaking at 20 km/h gusting to 40, then easing later
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Overnight low: 15°C
Tomorrow’s Forecast
Expected Conditions
Friday, August 8
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A mix of sun and cloud with a 40% chance of showers in the afternoon
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Continued risk of thunderstorms
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High: 27°C, but with a humidex of 35°C
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UV index holds at 7 or high
Friday Night
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Cloudy conditions persist
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Low: 20°C
Saturday, August 9
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Cloudy with a 40% chance of showers
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High: 26°C
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Night: Cloudy, low: 17°C
Sunday, August 10
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Cloudy again with a 30% chance of showers
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High: 25°C
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Partly cloudy overnight, low: 14°C
The weekend continues the humid, cloudy pattern, with rain chances slowly tapering by Sunday.
Wardrobe Recommendations
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Today: Prepare for high humidity—lightweight, breathable clothing is a must. If you’re heading out in the sun, sunscreen and a wide-brimmed hat are essential, especially before clouds increase in the afternoon. Keep an umbrella or light rain jacket close.
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Tonight: Slightly cooler but still damp—light layers and a windbreaker may come in handy.
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Friday through Sunday: With repeated chances of showers and continued humidity, go for quick-dry fabrics, rain gear, and comfortable footwear. Stay hydrated, and be mindful of local air quality if you’re sensitive to smoke or humidity.
Weather Trivia
Did you know?
Thunder Bay sits in the Lake Superior basin, which helps moderate extreme temperatures—but it also contributes to high humidity in summer. With warm air masses passing over the cooler lake water, fog and mist are common, especially during early mornings like today.






