From -5°C to +11°C Today — Classic Lakehead Spring Mood Swings
Pack Sunglasses and a Raincoat: Thunder Bay’s Forecast Has Layers
Thunder Bay, ON — April 11, 2025
A cold but clear start greets Thunder Bay this Friday morning, where the temperature at 6:00 AM EDT is -4.8°C, and with a wind chill of -9°C, you’ll definitely feel it in your fingertips. But don’t let the frosty start fool you — the day is on track to warm up nicely under mainly sunny skies.
Current humidity is at a high 95%, and winds are coming from the WSW at 9 km/h, keeping the chill in the air early on. Visibility is a healthy 24 km, and those pesky fog patches are expected to lift later this morning. Barometric pressure is at 102.4 kPa and falling, indicating a shift in weather patterns as we roll into the weekend.
By mid-afternoon, you can expect the temperature to rise to 11°C, a very comfortable spring day once the morning crispness fades. Winds will remain calm, with speeds up to 15 km/h, and the UV index is a moderate 4 — so not tropical, but sunscreen might not be the worst idea if you’re out enjoying the sunshine.
Tonight’s skies will feature just a few clouds, and temperatures will dip back down to a low of -1°C — so if you’re out stargazing or grilling in the backyard, a warm jacket is still essential.
Saturday takes a turn for the grey with mainly cloudy skies and a 40% chance of afternoon showers. Winds pick up a bit, coming from the south at 20 km/h by midday, with a slightly cooler high of 8°C. Saturday night remains cloudy with a 30% chance of showers and a low of +2°C.
Sunday carries on the cloudy trend, with a 40% chance of showers and a high of 9°C. By night, the chance of rain or snow jumps to 60%, with a low holding at +2°C, before rain or snow settles in Monday, reaching a high of just +3°C. Monday night cools further with periods of snow expected and a low of -6°C.
So how should you dress? Start the day in a warm coat — maybe even with gloves — and swap to lighter layers or a spring jacket by midday. Keep the rain gear handy for Saturday and Sunday, and maybe give your snow brush one last chance to shine Monday morning.
On this day in Thunder Bay’s weather history, the record high was 18.9°C, while the record low chilled the city to -15.0°C — a reminder that April in Northwestern Ontario still likes to dabble in both seasons at once.
Weather trivia for Thunder Bay buffs: Thanks to its location on the northwestern shore of Lake Superior, Thunder Bay often experiences “lake breezes” — cool winds that develop due to temperature differences between land and water, helping to moderate temperatures and occasionally stirring up fog or surprise drizzle, especially in spring.
