Thunder Bay Weather: A Cloudy Prelude to a Bright Spring Weekend
Thunder Bay, Ontario – April 24, 2025 – The Sleeping Giant stirs under a mostly cloudy sky this morning, shrouded in near-freezing air and a hint of drizzle. As of 6:00 AM at Thunder Bay Airport, the temperature is a crisp 0.6°C with the dew point sitting right behind at 0.5°C. That means the humidity is at a nearly saturated 99%—classic fog-fade conditions. Visibility stretches out to a generous 24 km, and a light breeze from the west at 6 km/h offers just enough movement to keep the morning stillness from turning spooky. Pressure is on the rise at 102.4 kPa—always a good sign when you’re hoping for stability and sun.
Today’s Forecast: Cloud Coverage With a Dash of Drizzle
This morning holds a 30 percent chance of showers or light drizzle as fog patches begin to lift. Thunder Bay will stay mostly cloudy through the day, with a high reaching 12°C. That’s warm enough to flirt with patio seating, but keep a hoodie close just in case. The UV index will rise to 4—moderate enough to warrant a touch of sunscreen if you’re soaking in those brief sunny breaks.
Tonight: Cool, Cloudy, and a Little Foggy
Skies remain mostly cloudy tonight, and the fog might just make a late-night comeback. Overnight temperatures are expected to settle around 0°C—no frost advisory, but it’s definitely not short-sleeves weather. Keep the layers on standby if you’re planning any outdoor night-time wanderings.
Friday Forecast: Steady and Slightly Warmer
Friday continues the theme with mainly cloudy skies. Fog patches will once again dissipate through the morning, making way for a brighter midday. The high will nudge up to 13°C, and with a UV index of 5, sunglasses should definitely be part of your outfit. The night clears out nicely with a low of +1°C, setting the stage for a truly pleasant weekend.
The Weekend Outlook: Spring Perfection (Almost)
Saturday, April 26: Pure sunshine graces the city with a beautiful high of 14°C. Break out the bike, fire up the grill, or hit the trails—this is your “no excuses” day to get outside.
Saturday Night: Clear skies persist and the temperature dips to a refreshing +1°C. If you’re planning a campfire, this is your night.
Sunday, April 27: A mix of sun and cloud with a 30 percent chance of showers. The high will be 13°C—still comfortable for most outdoor plans. Sunday night turns cloudier with a 40 percent chance of showers and a mild low of +5°C.
What to Wear in Thunder Bay
Morning fog and near-zero temperatures mean you’ll want to start with a warm jacket or fleece. As the day warms, lighter layers will do the trick. Waterproof shoes wouldn’t hurt in case the drizzle swings by, and toss in your sunglasses for Friday and the weekend—just in case the clouds let go and let the sun shine through.
Historic Highs and Freezing Lows
On April 24, Thunder Bay has historically seen it all—from a spring-ready high of 25.3°C in 1990 to a bone-chilling low of -12.2°C back in 1956. Today’s 12°C? Right in the sweet spot for seasonal sanity.
Weather Trivia: Thunder Bay’s Cloudy Secret
Did you know Thunder Bay’s unique geography often traps cooler air near the surface, leading to extended foggy and cloudy conditions in spring? That’s what happens when the lake breeze meets rising inland heat—a moody microclimate with a flair for suspense.
