A Rollercoaster Start to May in the Bay
Thursday, May 1, 2025 – From Cloudy to Showery with a Touch of Sunshine
Thunder Bay is starting off May with a frosty nip in the air, sitting at 1.4°C as of 6:00 AM, according to observations from Thunder Bay Airport. The dew point is nearly identical at 1.3°C, with a humidity level of 99%, so it’s no surprise the air feels moist and heavy. Visibility is solid at 24 km under mostly cloudy skies, and winds are light from the northwest at 5 km/h for now.
Pressure is currently at 101.3 kPa and falling—a sure sign that change is in the air. Today will feature a mix of sun and cloud with a 30 percent chance of morning showers. Winds will pick up from the east at 20 km/h by late morning, nudging the high to a respectable 11°C. Despite the chilly start, the UV index will reach 6—classified as high—so keep those sunglasses handy and sunscreen within reach if the clouds part.
Tonight: Clouding Over with Rain Creeping In
Thunder Bay’s skies will cloud up again this evening, with a 40 percent chance of showers before midnight. That will shift to more consistent rain overnight. The low will hover around 3°C—relatively mild, but just a prelude to Friday’s forecast curveball.
Friday: A Wintry Twist in May
Friday, May 2, will serve up a strange seasonal mash-up. Rain is expected to transition into periods of snow mixed with rain during the morning, then taper off by late afternoon. Temperatures will hold steady around 4°C, making it a raw and damp day. The UV index drops to 2—low—so it’s a day for indoor plans, or at the very least, a sturdy umbrella and a warm coat.
Friday night will bring clearing skies, but a chilly low of -2°C. It’s a sharp dip, so keep those frost-sensitive plants sheltered for one more night.
Weekend Warmth Returns
Saturday sees a dramatic improvement, with bright sunshine and a high of 17°C—perfect weather for shaking off the winter blues. Saturday night remains clear and comfortably cool at 2°C. Sunday offers more sunshine, though slightly cooler, with a high of 10°C and another clear evening at 6°C.
Historic Weather Snapshot
May 1 in Thunder Bay has a wide historical temperature range. The warmest was a balmy 25.0°C back in 1998, while the coldest scraped in at -10.6°C in 1967. Today’s conditions sit somewhere between the two, but that brief snow forecast for Friday keeps the tradition of unpredictability alive and well.
What to Wear?
It’s a day for layers—start with a warm base this morning, a rain jacket by afternoon, and perhaps some waterproof shoes just in case. You’ll want to upgrade to a heavier coat Friday, but by Saturday, it’s time to break out the spring attire and sunglasses.
Weather Trivia: Thunder Bay’s Spring Snow Streak
Did you know Thunder Bay has recorded snow as late as May 28? Spring snow isn’t just possible—it’s practically a tradition. Friday’s forecast keeps that streak alive!
