Winds Pick Up as Thunder Bay Shifts Into September Chill

Thunder Bay, Ontario – Tuesday, September 2, 2025 (10:00 PM EDT) – After a soggy day in the city, Thunder Bay is wrapping up Tuesday under light rainshowers and the subtle drama of shifting winds. At the Thunder Bay Airport, the temperature sits at 15.6°C, with air so damp you could practically drink it—humidity is at a near-saturated 98%, and the dew point is 15.3°C, just a whisker below the actual air temperature. Visibility remains decent at 24 km, but don’t get too comfortable—fall is sneaking in behind tonight’s passing weather system.

A southwest wind at 10 km/h is soon expected to swing around and intensify from the northwest, reaching 30 km/h gusting to 50 km/h by midnight. The barometric pressure is falling at 100.7 kPa, hinting at cooler, blustery conditions on the horizon. Autumn, it seems, is ready for its entrance.

Tonight’s Forecast – Rain Tapers, Wind Ramps Up

This evening’s showers, which could total 15 to 25 mm, are expected to shift to a 40% chance of scattered showers after midnight. There’s still a risk of a thunderstorm as the front moves through. The wind—currently mild—will become light early tonight before turning northwest and increasing to 30 km/h gusting to 50 just as many are trying to sleep. Temperatures will drop to a chilly low of 7°C, so be sure to close your windows unless you enjoy being a popsicle.

Wednesday – Gusty and Grey With Lingering Showers

Wednesday, September 3rd, won’t be winning any beauty contests. The skies stay cloudy, and there’s a 60% chance of showers throughout the day. Blame it on the brisk north wind at 30 km/h, gusting up to 50, bringing with it a definitive cool-down. The high will only reach 11°C, and with the wind, it’s going to feel like single digits, even if the calendar still says summer. The UV index is a modest 3, so sunglasses can take the day off.

Wednesday night won’t improve much. The cloud cover continues, and showers remain likely with a 60% chance. Winds will settle slightly to northwest 20 km/h, gusting to 40, and then lighten by evening. Overnight low? A frosty +3°C—jacket weather, no doubt.

Thursday and Friday – Cloudy, Cool, and Consistently Unsettled

Thursday, September 4th, sticks with the cloudy theme, along with a 40% chance of showers and a high of 13°C. Overnight, expect a low near +4°C and a continued 30% chance of precipitation.

Friday, September 5th, finally brings a little variety, with a mix of sun and cloud and yet another 40% chance of scattered showers. The daytime high improves slightly to 14°C, and the overnight low climbs to 8°C. So yes, technically warmer—but you’ll still want that hoodie.

Weather Stats & Historical Perspective

• Current Temperature: 15.6°C

• Wind: SW 10 km/h (shifting to NW 30 km/h gusting 50 overnight)

• Pressure: 100.7 kPa, falling

• Humidity: 98%

• Visibility: 24 km

• Historic High for Sept 2: 30.6°C (1983)

• Historic Low for Sept 2: 2.0°C (1964)

What to Wear in Thunder Bay This Week?

Say goodbye to tank tops and hello to layers, waterproof outerwear, and maybe even a toque by Wednesday night. The mix of wind and showers means you’ll want something that blocks the breeze and shrugs off drizzle. Footwear? Waterproof and non-slip is the way to go—mud puddles are the unofficial mascot of this week’s weather.

Weather Trivia – Lake Superior’s Temperament

Did you know? Lake Superior’s enormous surface area can dramatically influence Thunder Bay’s fall weather, especially when cold air moves over warm water. This combo can create instability that fuels cloud cover and showers, often making the shift to autumn feel extra damp and drawn out.