Thunder Bay – Weather Desk – Thunder Bay is in the grip of summer heat this morning, and an Orange Heat Warning is in effect for the City of Thunder Bay. At 6:00 AM EDT, the temperature was already 23.3°C, with a humidex of 31 and local smoke reducing visibility to 10 km.
Today is expected to be the peak of this heat event, with temperatures climbing toward 38°C and humidex values near 39. Some areas could approach 40°C, creating dangerous heat conditions. If you are looking for cooler air, the best local advice is simple: get closer to the shore of Lake Superior, where the lake may offer some relief from the inland heat.
Today’s Weather Overview
Current Conditions
At 6:00 AM EDT, Thunder Bay reported smoke with a temperature of 23.3°C. The dew point was 20.1°C, and humidity was 82 percent, creating a humid and heavy feel to the morning.
Winds were from the west-southwest at 14 km/h, with pressure at 101.5 kPa and rising. Visibility was reduced to 10 km due to smoke.
Today’s forecast calls for mainly sunny skies with local smoke. Winds will become west at 30 km/h, gusting to 50 km/h this morning. The high will reach 38°C, with a humidex of 39. The UV index is 9, or very high.
Orange Warning — Heat
Impact Level: High
Forecast Confidence: High
A heat event continues across Thunder Bay.
Expected conditions include:
Maximum temperatures of 34°C to 40°C
Minimum temperatures of 19°C to 23°C
Humidex values of 38 to 45
The warning is expected to continue through Tuesday evening. Today is forecast to be the hottest day, with temperatures possibly approaching 40°C in some areas. Tuesday remains hot, though it may be several degrees cooler than today.
Hot and humid air can also worsen air quality. With wildfire smoke in the area, residents should prioritize staying cool while also limiting smoke exposure when possible.
Extended Forecast
Expected Conditions
Tonight: Thunder Bay will see partly cloudy skies with a 30 percent chance of showers overnight and a risk of a thunderstorm. Local smoke will continue this evening. West winds at 20 km/h will become light this evening. The overnight low will be 22°C, offering little relief from the heat.
Tuesday, July 14: Expect a mix of sun and cloud with a 30 percent chance of showers early in the morning and a risk of a thunderstorm. Winds will become west at 20 km/h, gusting to 40 km/h, late in the morning. The high will reach 35°C, with a humidex of 39. The UV index remains 9, or very high.
Tuesday Night: Clear skies return, with a cooler low of 14°C.
Wednesday, July 15: Sunshine continues, with a high near 30°C. Wednesday night will be clear, with a low of 14°C.
Heat Safety
Extreme heat can affect everyone’s health. Check on older adults, people living alone, young children, outdoor workers, and anyone with medical conditions.
Watch for signs of heat exhaustion, including headache, nausea, dizziness, thirst, dark urine, and intense fatigue. Stop activity, move to a cooler place, and drink water.
Heat stroke is a medical emergency. Call 9-1-1 if someone has red, hot skin, confusion, dizziness, nausea, or a change in consciousness. While waiting for help, move the person to a cool place, remove extra clothing, and cool them with cold water or ice packs.
Never leave children, vulnerable people, or pets inside a parked vehicle.
Wardrobe Recommendations
Wear lightweight, light-coloured, loose-fitting clothing today. A wide-brimmed hat, sunglasses, and sunscreen are strongly recommended with the UV index at 9.
Drink water often, before you feel thirsty. Avoid heavy outdoor work during the hottest part of the day. Close blinds or shades, use fans or air conditioning, and move to a cooler public space if your home becomes too hot.
With smoke in the forecast, people with breathing or heart conditions should reduce strenuous outdoor activity.
Weather Trivia
Lake Superior is a powerful natural air conditioner for Thunder Bay. During summer heat events, areas close to the shoreline can be noticeably cooler than inland neighbourhoods because the lake warms more slowly than the land.
Summary: Thunder Bay weather for July 13, 2026: Orange Heat Warning in effect with smoke, 23°C early, high near 38°C, humidex 39, very high UV, gusty west winds, and dangerous heat continuing through Tuesday.
