Thunder Bay weather for June 29, 2026: mostly cloudy and 14°C early, cooler high of 18°C, shower and thunderstorm risk today
Thunder Bay – Weather – Thunder Bay begins Monday under mostly cloudy skies, with the temperature sitting near 14°C at the airport. The air is damp, pressure is falling, and the forecast points to an unsettled start to the week.
While today stays cooler with a high of only 18°C, warmer and more humid air arrives Tuesday, bringing showers, thunderstorm risk, and a humidex near 34.
Today’s Weather Overview
Current Conditions
At 6:00 AM EDT at Thunder Bay Airport, the temperature was 13.8°C under mostly cloudy skies. The dew point was 11.9°C, with humidity at 88 percent, giving the morning a cool and moist feel.
Winds were from the east at 9 km/h, visibility was excellent at 32 km, and the barometric pressure was 101.1 kPa and falling.
Today’s forecast calls for mainly cloudy skies with a 30 percent chance of showers late this morning and this afternoon. There is also a risk of a thunderstorm. The high will reach 18°C, with a UV index of 7, or high.
Tomorrow’s Forecast
Expected Conditions
Tonight: Clouds remain in place, with showers beginning late this evening. There is a risk of a thunderstorm late this evening and overnight, with local rainfall amounts of 15 to 25 mm possible. The overnight low will be a mild 17°C.
Tuesday, June 30: Showers will end in the morning, followed by a mix of sun and cloud. There is a risk of a thunderstorm early in the morning. The temperature will climb sharply to 29°C, with a humidex of 34. The UV index is 9, or very high. Tuesday night brings cloudy periods with a 30 percent chance of showers and a low of 14°C.
Wednesday, July 1: Canada Day looks bright and warm, with sunny skies and a high of 29°C. Wednesday night brings cloudy periods and a low of 15°C.
Thursday, July 2: Expect a 30 percent chance of showers with a high near 27°C. Thursday night also carries a 30 percent chance of showers and a low of 14°C.
Wardrobe Recommendations
Today calls for light layers and a rain jacket or compact umbrella, especially for late morning, afternoon, and evening plans. It will feel cooler than the next couple of days, so a hoodie or light jacket will be useful.
For Tuesday, switch to lightweight, breathable clothing as humidity builds. With a very high UV index, sunglasses, sunscreen, and a hat will be important. Keep rain gear handy overnight and early Tuesday due to showers and thunderstorm risk.
Weather Trivia
Thunder Bay can see sharp weather changes when cooler Lake Superior air gives way to warmer, humid air from the south. That kind of transition can help fuel showers and thunderstorms, especially when pressure is falling and moisture is increasing.
