Sunny skies and 20°C today with clear nights, warmer temperatures this weekend, and highs reaching 24°C next week.
THUNDER BAY – WEATHER – Northwestern Ontario continues its gradual transition toward more seasonable late-May weather as Thunder Bay enjoys another sunny day with temperatures climbing to 20°C. While the lingering chill of Lake Superior still influences overnight temperatures, a warmer pattern is building toward the weekend.
At 6:00 AM EDT at Thunder Bay Airport, conditions were mainly clear with a temperature of 5.8°C. Humidity sat at 97%, creating a cool early morning feel despite clear skies. Winds were light from the west-southwest at 5 km/h, visibility was an excellent 32 kilometres, and barometric pressure measured 101.9 kPa and rising, a sign of stable weather continuing across the region.
Today’s Weather Overview
Current Conditions
Thunder Bay wakes up under mostly clear skies and calm conditions this morning. Sunshine dominates the forecast with winds shifting east to 20 km/h later this morning.
Wednesday Forecast
- Conditions: Sunny
- High: 20°C
- Wind: East 20 km/h
- UV Index: 6 (High)
It is a classic Northwestern Ontario spring day — cool to start but comfortable by afternoon.
Tonight’s Outlook
Clear skies continue overnight as northeast winds at 20 km/h become light late this evening.
- Low: 6°C
- Excellent evening weather for walking, patio dining, or enjoying the sunset along the Lake Superior waterfront.
Thursday Forecast
Another beautiful day arrives Thursday.
Thursday – May 28
- Conditions: Sunny
- High: 18°C
- UV Index: 7 (High)
Thursday runs slightly cooler than Wednesday but remains ideal for outdoor plans.
Thursday Night
- Clear skies
- Low: 9°C
Looking Ahead – Warmer Air Building
Friday – May 29
- Mix of sun and cloud
- 30% chance of showers
- High: 24°C
Saturday – May 30
- 30% chance of showers
- High: 23°C
Sunday – May 31
- Sunny
- High: 19°C
Monday – June 1
- Sunny
- High: 19°C
Tuesday – June 2
- Sunny and warmer
- High: 24°C
The weekend brings a slight risk of showers but temperatures remain very pleasant. Early June is shaping up with strong summer-like potential.
Wardrobe Recommendations
Morning commuters will still want a light jacket or sweater as temperatures begin in the single digits.
By midday:
- Sunglasses recommended
- Sunscreen important with UV values reaching High
- Light spring clothing works well this afternoon
For evening activities near Lake Superior, keep an extra layer handy as temperatures cool quickly after sunset.
Lake Superior Weather Impact
Lake Superior continues to play its familiar role moderating Thunder Bay temperatures. Inland communities may warm faster, but cooler lake air can hold shoreline temperatures down, especially in the mornings and evenings.
As warmer air arrives Friday and into next week, Thunder Bay may finally begin seeing more consistent late-spring warmth.
Weather Trivia
Did you know?
Thunder Bay’s proximity to Lake Superior often creates temperature differences of 5°C to 10°C between areas near the lake and communities farther inland during spring. The lake retains winter cold deep into May, slowing seasonal warming.
