Thunder Bay heads into the weekend with a cool and comfortable Friday morning, but summer heat will build by Sunday. At 6:00 AM EDT, the temperature was 12.1°C under partly cloudy skies, with high humidity and light southwest winds. Today and Saturday look mainly sunny, while Sunday brings hotter weather and a slight chance of showers.
Today’s Weather Overview
Current Conditions
At 6:00 AM EDT, Thunder Bay reported partly cloudy skies with a temperature of 12.1°C. The dew point was 11.3°C, and humidity was 95 percent, giving the morning a damp but calm feel.
Winds were from the southwest at 6 km/h, visibility was excellent at 32 km, and the barometric pressure was 101.4 kPa and falling.
Today’s forecast calls for mainly sunny skies with a high of 26°C. The UV index is 8, or very high, so sun protection is important through the late morning and afternoon.
Weekend Forecast
Expected Conditions
Tonight: A few clouds are expected, with a cool overnight low of 11°C.
Saturday, July 11: Thunder Bay will see another pleasant day with mainly sunny skies. The high will reach 25°C, with a humidex of 27. The UV index remains 8, or very high. Saturday night brings cloudy periods with a 30 percent chance of showers and a low of 14°C.
Sunday, July 12: Sunday turns warmer, with a mix of sun and cloud and a 30 percent chance of showers. The high will climb to 30°C, making it the hottest day of the weekend. Sunday night brings cloudy periods with a 30 percent chance of showers and a mild low of 17°C.
Monday, July 13: The hot summer pattern continues with sunny skies and a high near 31°C.
Wardrobe Recommendations
For Friday and Saturday, light summer clothing will be comfortable by afternoon, but a light sweater or jacket may be useful early in the morning and later at night.
With the UV index at 8, wear sunscreen, sunglasses, and a hat if you are outdoors. By Sunday, plan for hotter conditions with breathable clothing and plenty of water. Keep a compact umbrella nearby Saturday night and Sunday, when shower chances return.
Weather Trivia
Thunder Bay can often start July mornings on the cool side because of nearby Lake Superior, but inland warmth can build quickly by afternoon. That contrast is on display this weekend, with morning lows near 11°C followed by daytime highs climbing toward 30°C.
Overview: Thunder Bay weekend weather update for July 10–13, 2026: mainly sunny Friday and Saturday, high UV, cooler nights, then hotter Sunday with a high of 30°C and a 30% chance of showers.
