Fog Fades, Clouds Part, and a Gentle Warm-Up Begins

THUNDER BAY – WEATHER – If you’re out early in Thunder Bay this morning, you’ll need your fog lights and a bit of patience. The city is waking up under a soft misty blanket, with visibility at just 5 km, and the air is thick with moisture. But fear not—this classic Lake Superior fog won’t stick around long. By mid-morning, expect conditions to improve as the skies begin to brighten and the temperature climbs.

Misty Start to a Cool Morning

At 5:00 AM EDT, conditions at Thunder Bay Airport were misty and damp, with a temperature of 10.6°C, matching the dew point—a sure sign of 100% humidity. Winds are coming from the north-northwest at 8 km/h, barely stirring the air, and pressure is holding steady at 101.9 kPa.

The fog patches will dissipate later this morning, making way for a mix of sun and cloud as the day progresses. Temperatures will climb to a pleasant high of 18°C, ideal for an autumn hike or a quiet walk along the waterfront. The UV index is moderate at 5, so don’t forget a bit of sunscreen if you’re out during peak hours.

Historical note: Thunder Bay has seen both chilly 2°C mornings and sunny 25°C afternoons on this date over the years. Today’s weather lands us comfortably in the middle of that wide September range.

Tonight: Fog Returns with Cloudy Skies

Tonight, the skies remain cloudy, and fog patches are expected to develop again after midnight. If you’re heading out late or starting early Monday, expect reduced visibility. The low will be a mild 13°C, continuing the city’s recent trend of unseasonably warm nights.

Monday Through Wednesday: Cloudy but Warming

Monday, September 15, brings cloudy skies all day, but temperatures rise to a comfortable 23°C—not bad for a mid-September Monday. Monday night stays cloudy, with a low of 14°C.

Tuesday, September 16, continues the cloudy theme, but brings even more warmth, with a high of 25°C—a taste of summer in disguise. The night stays cloudy, with a low of 14°C.

Wednesday, September 17, sees continued cloud cover, with a 30 percent chance of showers. The high will dip slightly to 22°C, and there’s a 40 percent chance of showers Wednesday night, with a low of 13°C.

What to Wear?

Start your Sunday with light layers and a windbreaker to cut the morning chill and mist. By afternoon, a sweater or long sleeve should do the trick. Keep waterproof shoes handy for early fog, and maybe keep a compact umbrella in your Monday-Tuesday backpack—just in case those clouds get ideas.

Weather Trivia: Thunder Bay’s Misty Mornings

Thunder Bay’s early morning mists are a classic Lake Superior effect. As the lake retains summer warmth while the land cools quickly overnight, moisture condenses near the surface, creating radiation fog. It’s nature’s way of hitting the snooze button on the day—so embrace the moodiness with a hot coffee and a bit of extra time.