Thunder Bay weather for July 27, 2026: A yellow fog advisory, light rain and reduced visibility this morning
Thunder Bay – Weather – Thunder Bay begins Monday under damp and foggy conditions, with a yellow fog advisory in effect for the city and nearby areas along the Lake Superior shoreline. Light rain, complete humidity saturation and reduced visibility are creating a grey start to the day.
Environment Canada reports that dense fog moving inland from Lake Superior may produce near-zero visibility in some locations, including sections of Highway 17. Conditions should gradually improve as the fog lifts Monday morning.
Today’s Weather Overview
Current Conditions
As of 6:39 a.m. EDT on Monday, July 27, 2026, Thunder Bay was reporting a temperature of 14.1°C with a light rainshower.
The dew point was also 14.1°C, producing 100 per cent humidity. With the air fully saturated, fog and low cloud are limiting visibility to approximately three kilometres, with locally poorer conditions possible.
Winds are light from the east-northeast at 5 km/h. Barometric pressure is 100.9 kPa and falling, suggesting that unsettled weather remains possible.
Drivers should use extra caution where fog is present. Turn on headlights, reduce speed and leave additional space between vehicles.
Monday will remain mainly cloudy, with a 30 per cent chance of showers and a risk of a thunderstorm. Fog patches should dissipate during the morning.
The afternoon high will reach 24°C, although the humidex may make it feel closer to 29. The UV index will be 7, or high, meaning sun protection will still be important during brighter periods.
Tonight will be partly cloudy before skies become clear during the evening. The overnight low will fall to 12°C.
Tomorrow’s Forecast
Expected Conditions
Tuesday, July 28
Tuesday will begin sunny before a mix of sun and cloud develops around noon. The daytime high will reach 25°C, with a humidex of 30.
The UV index will rise to 8, or very high. Sunscreen, sunglasses and shade will be important, particularly during the middle of the day.
Cloudy periods are expected Tuesday night, with a 30 per cent chance of showers and a low of 14°C.
Wednesday, July 29
Wednesday will be warmer, with a high of 27°C and a 30 per cent chance of showers.
Cloudy periods are expected Wednesday night, with temperatures falling to approximately 15°C.
Thursday, July 30
Thursday will remain warm and somewhat unsettled. The forecast calls for a 40 per cent chance of showers and a high of 27°C.
Thursday night will have a 30 per cent chance of showers, with a mild overnight low of 17°C.
Wardrobe Recommendations
A lightweight waterproof jacket or compact umbrella will be useful Monday because of the chance of showers and thunderstorms. Breathable clothing is recommended as the humidex approaches 29.
Drivers and pedestrians travelling early in the morning should consider reflective or bright clothing because fog may make people and vehicles more difficult to see.
For Tuesday, lighter summer clothing will be appropriate. Add sunscreen, sunglasses and a hat because the UV index is expected to reach very high levels.
Keep a light sweater or jacket available for the evenings, particularly Monday night when the temperature drops to 12°C.
Weather Trivia
Lake Superior can strongly influence Thunder Bay’s weather, especially during periods of fog.
Fog often develops when warm, moisture-filled air moves across the colder surface of the lake. The air cools to its dew point, causing water vapour to condense into tiny suspended droplets. Winds can then push this dense fog inland, quickly reducing visibility along the shoreline and nearby highways.
Forecast source: Environment Canada forecast issued at 5:30 a.m. EDT on Monday, July 27, 2026. Fog advisory issued at 8:46 p.m. EDT on Sunday, July 26, 2026.
