Sunny Skies and Spring Swings in Thunder Bay
Thunder Bay, ON – Monday, May 5, 2025 – It’s a chilly start in Thunder Bay today with clear skies and a temperature of -1.8°C as of 6:00 AM EDT. Humidity is at a moisture-laden 100%, and the barometric pressure is a solid 102.1 kPa and rising—great news for stability and sunshine. Winds are light from the southwest at just 3 km/h, offering little relief from that brisk morning air.
The wind chill makes it feel more like -3°C, so if you’re heading out early, gloves and a warm coat are still your best friends.
Visibility is excellent at 32 km, perfect for scenic views of Lake Superior or that early jog—if you’re brave enough to face the crisp air!
Sunshine Rules the Day – But You’ll Still Need Layers Early
Despite the frosty beginning, today’s forecast calls for a sunny sky with temperatures rebounding significantly, climbing to a high of 16°C. Winds will remain gentle, reaching up to 15 km/h. The UV index is high at 7, so don’t let the cool start fool you—sunscreen is still a wise choice.
By tonight, the skies remain clear and the temperature stays above freezing, settling at a low of +2°C—perfect for a peaceful evening under the stars without the risk of frost nipping at your nose (finally!).
Tuesday Gets Toasty Before Clouds Return
Tuesday, May 6, kicks off with more sunshine in the morning and early afternoon. By late in the day, clouds will mix in and there’s a 30% chance of showers. Temperatures surge to a warm high of 22°C, giving a proper taste of early summer to come. Winds will shift to the north, picking up to 20 km/h later in the morning, helping to usher in that weather change.
Tuesday night brings mostly cloudy skies and a mild low of +4°C. However, by Wednesday, things will clear up again, although it’ll be cooler with a daytime high of just 11°C. Expect a return to colder nights too—Wednesday’s overnight low is forecast to drop to -2°C, so the back-and-forth continues!
Historic Weather Extremes – A Day of Contrasts
Historically, May 5 in Thunder Bay has offered up some dramatic weather. The warmest recorded high for this date is 26.8°C in 2000, while the record low was a frosty -6.7°C in 1967. Today’s low of -1.8°C puts us on the chillier side of the spectrum, but that high of 16°C is pulling us into more seasonable territory.
Wardrobe Wisdom: Start with winter gear and transition to spring attire by noon. Sunglasses and sunscreen are essential. And keep the coat handy for Wednesday’s cold snap—you’ll be trading sandals for socks once again.
Thunder Bay Weather Trivia: Did you know Thunder Bay holds the Canadian record for the largest single-day temperature swing in May? A 27°C jump from dawn to afternoon once shocked locals in 1991. Classic Lake Superior mischief!
