Sunday Starts Frosty but a Warm-Up is in Sight
Thunder Bay, ON – Sunday, April 6, 2025 – This morning in Thunder Bay, the city wakes to a brisk -9.5°C under partly cloudy skies. With a light westerly wind of just 3 km/h, the wind chill dips to -11—just enough to nip at your nose if you’re stepping outside. The humidity is sitting high at 88%, and the dew point is a chilly -11.1°C, which means the air feels damp despite the cold. Visibility is excellent at 24 km, and atmospheric pressure is measured at 101.9 kPa and trending downward, signaling that changes are brewing.
Flurries and a Windy Turn This Afternoon
Sunday is shaping up to be a mixed bag, meteorologically speaking. Cloud cover will increase, and there’s a 60% chance of flurries by the afternoon. Winds will pick up from the north later today, reaching 20 km/h, which may add an extra bite to the breeze. The high will climb to +1°C—a modest improvement—but it won’t feel nearly that warm with wind chills starting at -14 this morning and staying around -8 through the day. The UV index will hit 4, which is considered moderate, so if you catch some rays during a sunny spell, don’t forget your SPF.
Tonight, expect partly cloudy skies to continue with the same 60% chance of flurries. North winds will intensify to 30 km/h, gusting up to 50 km/h. The temperature will drop to -9°C, but thanks to the wind, it’ll feel more like -17 overnight. A good night to let the fireplace do its thing.
Monday: Windy and Chilly but Some Sun Peeks Through
Monday offers a mix of sun and cloud, with temperatures falling back into negative territory. The high will be -3°C, and north winds at 20 km/h will make it feel like -17 in the morning and -8 by the afternoon. The UV index will be slightly lower at 3, still moderate. By Monday night, skies will clear and temperatures will drop further to -13°C—cold, yes, but at least clear and calm.
Midweek: Sunshine and the Start of a Spring Streak
Spring finally starts to show some consistency by Tuesday. Sunny skies will return, and the high will rise to +3°C, followed by another clear night with a low of -10°C. By Wednesday, we’re talking full sunshine and a high of 8°C, and the good vibes roll right into the back half of the week. Thursday and Friday will see a mix of sun and cloud with highs of 11°C and 12°C, respectively, and nighttime lows hovering just below or at zero. You can almost hear the snowbanks sweating.
April 6 in Thunder Bay Weather History
Thunder Bay has seen some real weather swings on this date. The warmest April 6 on record was a toasty 20.8°C in 1991—definitely ice cream weather. On the chillier side, the coldest was a frigid -28.9°C, logged in 1967. Today’s weather leans cool, but at least we’re not anywhere near record-breaking territory.
What to Wear in Thunder Bay Today
Layers are your best friend. Start with thermals, add a good insulated jacket, and don’t forget your gloves and hat. If you’re heading out in the evening, windproof gear is a smart choice as those gusts will definitely make their presence known.
Thunder Bay Weather Trivia
Did you know? Thunder Bay is one of the sunniest cities in Ontario during spring, often ranking just behind Windsor. It’s no wonder the city sees such dramatic snowmelt once the sun finally takes control—it’s bright, even when it’s brisk!
