Humidity Hangs On as Thunder Threatens Later Today
THUNDER BAY – WEATHER – Fog horns, anyone? Thunder Bay wakes up today under a misty shroud that has the city feeling like a scene from a maritime mystery novel. Friday is a day for rainwear and an umbrella.
With 100% humidity, the air is heavy, the roads are slick, and visibility is still low. But hang tight—things will clear a bit before the next wave of weather rolls in. Spoiler alert: it might come with thunder.
Morning Mist, Afternoon Storm Potential
At 7:27 AM EDT, conditions at Thunder Bay Airport were downright damp, with mist reported, a temperature of 12.1°C, and matching dew point—which means the atmosphere is saturated and foggy.
Visibility sits at 8 km, and a steady east wind at 13 km/h is keeping things cool and clammy. The barometric pressure is 102.2 kPa but falling, a classic sign that the stable weather won’t last.
As the fog patches dissipate through the morning, the clouds won’t be going far. Expect a cloudy day with a 60 percent chance of showers and a risk of a thunderstorm by this afternoon. Thunder Bay’s high will reach 18°C, but with the sticky air, it may feel warmer than that. The UV index is moderate at 4, so sunburn isn’t likely—but don’t expect much blue sky.
Historically speaking, Thunder Bay’s record high for September 12 is 28.3°C, while the record low is a crisp 0.6°C. Today’s forecast is a pretty typical taste of early fall—moody, moist, and unpredictable.
Evening Fog Rolls Back In
Tonight, the clouds hang around with a 40 percent chance of evening showers, and that thunderstorm risk continues into the early evening hours. As the night progresses, fog patches will redevelop, making for reduced visibility once again. The overnight low will be a mild 12°C, perfect for staying cozy indoors with a book or a late-night movie.
Weekend Outlook: Gradual Improvements
Saturday, September 13, starts cloudy once again, with fog patches clearing in the morning. But don’t let the gloom fool you—things will warm up nicely. The high will rise to 21°C, and with a humidex of 25, it’ll feel more like a mid-summer rerun than a fall preview. Saturday night clears out completely, offering up a refreshing low of 11°C under starry skies.
Sunday, September 14, features a mix of sun and cloud with a cooler high of 17°C, and the evening will see cloudy periods with a low of 12°C.
And good news, weather watchers—Monday, September 15, brings a return of sunshine and warmth. Expect a mix of sun and cloud with a high of 23°C, perfect for sneaking in one last BBQ or bike ride before the season shifts. Monday night will be cloudy with a low of 14°C, holding onto that pleasant overnight warmth.
What to Wear?
Today calls for waterproof outerwear and layers—think rain jacket over something breathable. Umbrella? Definitely. The humid conditions could make things feel muggy, so avoid heavy fabrics. As the weekend dries out, your go-to fall flannel will come back into fashion rotation—especially by Sunday.
Weather Trivia: Thunder Bay’s Foggy Reputation
Thunder Bay isn’t just foggy today—it’s foggy a lot. Thanks to its proximity to Lake Superior, the city experiences frequent radiation and advection fog, particularly in late summer and early fall. Lake-cooled air mixing with warmer land surfaces creates the perfect storm for—you guessed it—misty mornings and foghorn moods.
