THUNDER BAY – WEATHER – Could real spring weather finally be here? Today’s forecast suggests it just might.
Thunder Bay is starting Tuesday with a crisp spring chill, but the day is set to turn much milder. After a morning temperature near -2°C and a wind chill of -5, sunshine will help lift the city to a pleasant afternoon high of 16°C.
Today’s Weather Overview
Current Conditions
As of 7:00 AM EDT Tuesday, April 21, 2026, Thunder Bay was reporting sunny skies and a temperature of -2.3°C.
The dew point is -4.6°C, with humidity at 84%, giving the morning a cool and slightly damp feel. Winds are light from the west-southwest at 8 km/h, producing a wind chill of -5.
Visibility is excellent at 32 km. Barometric pressure is 101.1 kPa and falling, suggesting a gradual shift in the weather pattern later in the week.
Today’s Forecast
Thunder Bay will enjoy a sunny Tuesday, with the wind becoming northwest at 20 km/h late this morning.
The high will reach 16°C, making this one of the more spring-like days of the week. Early risers will still feel the chill, with a morning wind chill near -7.
The UV index is 5, or moderate, so sunglasses are a good idea, and sunscreen may be useful for anyone spending extended time outdoors.
Tonight’s Forecast
Tonight will stay clear, with temperatures dropping back below freezing. The overnight low is expected near -1°C.
Wednesday Outlook
Wednesday will begin sunny, then become a mix of sun and cloud in the afternoon. The daytime high will reach 12°C.
The UV index climbs to 6, or high, meaning sun protection becomes more important, especially during the midday and afternoon hours.
Wednesday night turns cloudier, with a 30 percent chance of showers and a low of +2°C.
Thursday Outlook
Thursday brings a more unsettled pattern. Expect a mix of sun and cloud with a 60 percent chance of showers and a high of 14°C.
Thursday night remains cloudy with a 40 percent chance of showers and a mild low near 7°C.
Looking Ahead
The mild spring pattern continues into Friday, with a high near 11°C and a 60 percent chance of showers. Cooler air returns by the weekend, with Saturday bringing a 40 percent chance of rain showers or flurries and a high near 6°C.
Sunday and Monday look calmer, with a mix of sun and cloud and daytime highs near 7°C to 8°C.
Weather Alerts and Hazards
No weather warning text was included with this update. The main concern today is the frosty morning start, followed by strong spring sunshine and a moderate UV index.
Drivers may still find a few slick spots early this morning in shaded areas, but conditions should improve quickly as temperatures rise.
Wardrobe Recommendations
Start the morning with a warm jacket, gloves, and perhaps a toque if you are heading out early. By afternoon, lighter spring layers should be enough as temperatures climb to 16°C.
Sunglasses will be useful today, and a waterproof jacket may be worth keeping handy later this week as shower chances increase.
Weather Trivia
Thunder Bay’s April weather can swing quickly from winter chill to spring warmth. A morning wind chill near -7followed by an afternoon high of 16°C is a classic Northwestern Ontario spring setup — scrape the windshield at breakfast, open the jacket by lunch..
