Visibility is the main concern for the Thursday morning commute. Western Lake Superior remains below strong-wind-warning criteria, with modest offshore winds and waves
THUNDER BAY – WEATHER DESK – Thursday, September 24, 2026 – Thunder Bay starts Thursday with cool temperatures and thick patches of mist. Drivers should allow extra time until visibility improves.
The morning commute was not as chilly as the early morning temperature would suggest.
A mix of sun and cloud is expected after the fog clears, with a high of 17 C. Showers become possible tonight. Friday will be cloudy but much warmer, with a high of 21 C and a Humidex of 25. Saturday remains cloudy and slightly cooler.
Current Conditions: Mist Reduces Visibility
At 5:00 a.m. EDT, Thunder Bay Airport reported mist and a temperature of 2.7 C. Humidity was 100 per cent, the west wind was 4 km/h and visibility was reduced to 1.6 kilometres.
The atmospheric pressure was 103.1 kPa and falling. The temperature and dew point were both 2.7 C, which supported the development of mist and fog.
Environment and Climate Change Canada expects the fog patches to dissipate this morning.
Thursday, September 24: Fog Clears, Showers Return Tonight
Thursday will bring a mix of sun and cloud after the morning fog patches dissipate. The high will reach 17 C. The UV index will be 5, or moderate.
Clouds will increase tonight. There is a 60 per cent chance of showers, changing to a 30 per cent chance of drizzle near midnight. The overnight low will be 10 C.
The public forecast does not identify a significant wind or gust threat for the city during this period.
Friday, September 25: Cloudy and Unseasonably Mild
Friday will be cloudy with a high of 21 C. The Humidex will make it feel closer to 25. The UV index will be 3, or moderate.
Friday night will remain cloudy with a low of 8 C.
Saturday, September 26: Cloudy With Evening Shower Risk
Saturday will be cloudy with a high of 18 C. Saturday night will remain cloudy with a 30 per cent chance of showers and a low of 8 C.
Three-Day Thunder Bay Forecast at a Glance
| Day | Conditions | High | Night |
|---|---|---|---|
| Thursday, Sept. 24 | Morning fog patches, then a mix of sun and cloud | 17 C | 60% chance of showers, changing to 30% chance of drizzle; low 10 C |
| Friday, Sept. 25 | Cloudy; Humidex 25 | 21 C | Cloudy; low 8 C |
| Saturday, Sept. 26 | Cloudy | 18 C | Cloudy with 30% chance of showers; low 8 C |
Air Quality: Low Risk in the Latest Available Forecast
The latest Environment and Climate Change Canada AQHI forecast available during the early-morning check placed Thunder Bay at 2, or low risk, for Thursday.
At this level, the general population can continue normal outdoor activities. People with heart or breathing conditions should follow their usual medical advice and pay attention to symptoms.
The AQHI page had not yet displayed a newly issued Thursday-morning forecast when this article was prepared. The editor should refresh the AQHI before publication.
Travel Conditions: Slow Down in Morning Fog
Visibility of 1.6 kilometres at Thunder Bay Airport means some parts of the city and surrounding rural roads may have thicker fog than others.
- Use low-beam headlights and make sure all vehicle lights are on;
- Reduce speed and leave more room between vehicles;
- Watch for pedestrians, cyclists and school buses emerging from fog;
- Avoid stopping on the travelled portion of a road; and
- Expect wet pavement tonight where showers develop.
No snow, freezing rain or damaging wind threat is indicated in the three-day city forecast.
Western Lake Superior Marine Forecast
Marine warnings: No strong wind warning, watch or other marine warning was in effect for Western Lake Superior in the 3:00 a.m. EDT forecast issued September 24.
Thursday: South wind 10 knots will back to southeast 10 knots this afternoon.
Tonight: Southeast wind 10 knots will veer to south 10 knots near midnight and become light overnight. Scattered showers are expected.
Friday: Light winds are forecast.
Waves: Offshore waves will be 0.5 metres or less through Thursday and tonight, then subside to less than 0.5 metres Friday morning.
Weather and visibility: Scattered showers are forecast tonight. The marine bulletin does not call for fog or another specific visibility restriction over Western Lake Superior during the forecast period.
Extended wind outlook: Light winds are forecast Saturday. South winds of 15 knots are expected Sunday before diminishing to light. Light winds are forecast Monday.
Thunder Bay Harbour and the Open Lake Can Be Different
The Western Lake Superior forecast describes offshore conditions. Thunder Bay Harbour, the marina and protected bays may be calmer because of the breakwall, islands and shoreline.
Conditions can change near the harbour entrance and along exposed shorelines. A south or southeast wind can also affect different parts of the harbour and open lake in different ways.
Today’s 10-knot winds and waves of 0.5 metres or less do not represent a severe marine event. They may still produce uncomfortable conditions for small canoes, kayaks, paddleboards and lightly loaded boats, especially farther from shelter. Cold Lake Superior water increases the consequences of a capsize even when the air is mild.
Boating Safety Guidance
- Wear an approved personal flotation device;
- Check the newest marine forecast and local observations immediately before departure;
- Carry reliable communications and tell someone your route and expected return time;
- Use navigation lights in poor visibility and near sunrise or sunset;
- Prepare for scattered showers tonight; and
- Do not assume sheltered conditions at the marina represent the open lake.
Thunder Bay Weather, Thunder Bay Forecast, Lake Superior Marine Forecast, Western Lake Superior, Thunder Bay Harbour, Morning Fog, Travel Conditions, Boating Safety, Air Quality, Northwestern Ontario Weather
Sources Checked
- Environment and Climate Change Canada – Thunder Bay forecast and airport observation, forecast issued at 5:30 a.m. EDT and observation reported at 5:00 a.m. EDT on September 24, 2026;
- Environment and Climate Change Canada – active weather alerts;
- Environment and Climate Change Canada – Thunder Bay Air Quality Health Index; and
- Environment and Climate Change Canada – Western Lake Superior marine forecast, issued at 3:00 a.m. EDT on September 24, 2026.
