THUNDER BAY – WEATHER – Thunder Bay is starting Friday on a damp and chilly note, with mostly cloudy skies, gusty easterly winds, and temperatures hovering just above freezing. The bigger story is the weather swing ahead: showers and steady rain today, then a fast-moving cooldown tonight that could bring flurries, freezing drizzle, and a biting northwest wind into Saturday.
Today’s Weather Overview
Current Conditions
As of 7:00 AM EDT Friday, April 17, 2026, Thunder Bay was sitting at 1.7°C under mostly cloudy skies. The air remains moist, with a dew point of 0.1°C and humidity at 89%, helping create that raw, early-spring feel. Winds from the east at 24 km/h, gusting to 35 km/h, are adding to the chill, while visibility is a solid 32 km. Barometric pressure is 101.0 kPa and rising, suggesting changing conditions as the day unfolds.
Through the morning, a few showers will taper off before skies stay mostly cloudy. By this afternoon, periods of rain return, and there is also a risk of a thunderstorm. Fog patches will gradually dissipate near noon. The daytime high is expected to reach 8°C, which will feel fairly mild compared to what follows tonight.
Tomorrow’s Forecast
Expected Conditions
Tonight:
Rain continues into the evening before ending near midnight. After that, Thunder Bay will remain cloudy with a 40 percent chance of rain showers after midnight, shifting to a 30 percent chance of flurries overnight. There is also a risk of freezing drizzle overnight, which could create slippery spots on untreated surfaces. A risk of thunderstormlingers early in the evening. Winds will swing around to the northwest at 30 km/h, gusting to 50 km/h, bringing in sharply colder air. The low falls to -4°C, with an overnight wind chill near -9.
Saturday, April 18:
Saturday will feel much more like late winter than mid-April. Expect mainly cloudy skies with a 30 percent chance of flurries. Winds from the west at 30 km/h will keep it brisk, and the high will reach only 1°C. Morning and exposed areas may feel closer to -10 with the wind chill.
Saturday Night:
Cloudy periods continue with a 40 percent chance of flurries and a low of -9°C.
Sunday, April 19:
Conditions improve slightly, but the cold remains. Expect a mix of sun and cloud with a 30 percent chance of flurriesand a daytime high of 3°C.
Sunday Night:
Clear skies return, but temperatures drop sharply again to -9°C.
Weather Risks and Alerts
No formal alert text was included in the forecast information provided, but Thunder Bay still faces a few notable weather hazards over the next 24 hours:
- Risk of thunderstorm this afternoon and evening
- Risk of freezing drizzle overnight
- Strong northwest winds gusting to 50 km/h tonight
- Rapid drop from rain to flurries and subzero temperatures
That combination could make for slick roads, icy sidewalks, and reduced comfort for anyone heading out late tonight or early Saturday.
Wardrobe Recommendations
Friday calls for a water-resistant jacket, layered clothing, and sturdy footwear for wet conditions. By tonight and into Saturday, it will be wise to switch back to winter-ready outerwear, including a warm coat, gloves, and boots with good traction. The return of gusty winds and below-freezing temperatures means lighter spring clothing will not be enough once the cold air arrives.
Weather Trivia
Thunder Bay’s location on the northwestern shore of Lake Superior often creates dramatic spring weather swings. In April, it is not unusual to move from rain and even a thunderstorm risk to flurries and freezing drizzle in less than 12 hours, especially when colder northwest air sweeps in behind a passing weather system.
