Thunder Bay – WEATHER – Thunder Bay begins Thursday with a mild and humid morning under mostly cloudy skies. The air has a damp feel, with humidity above 90 percent, while rising pressure hints at some gradual improvement.
However, the day will still carry an unsettled edge, with showers possible this afternoon and a risk of a thunderstorm.
Today’s Weather Overview
Current Conditions
As of 6:00 AM EDT, Thunder Bay is reporting mostly cloudy conditions with a temperature of 9.9°C. The dew point is 8.7°C, and humidity is at 92%, making the morning feel cool, damp, and springlike.
Winds are light from the west-southwest at 8 km/h, with visibility at 32 kilometres. The barometric pressure is 100.0 kPa and rising, suggesting the atmosphere is slowly stabilizing, though showers remain in the forecast.
Today will bring a mix of sun and cloud, with a 60 percent chance of showers this afternoon. There is also a risk of a thunderstorm later in the day. The high will reach 20°C, with a UV index of 7, rated high.
Tonight will be mainly cloudy early, with a 60 percent chance of showers and a continued risk of a thunderstormearly this evening. Conditions are expected to clear later this evening, with the overnight low dropping to 7°C.
Tomorrow’s Forecast
Expected Conditions
Friday will start sunny, then become a mix of sun and cloud late in the morning. Winds will be west at 20 km/h, becoming south at 20 km/h in the afternoon. The high will reach 20°C, and the UV index will remain high at 7.
Friday night will see increasing cloudiness, with a low of 9°C.
Saturday will turn cloudier again, with a 40 percent chance of showers and a high of 19°C. Saturday night will bring cloudy periods, a 30 percent chance of showers, and a low of 7°C.
Sunday will offer a mix of sun and cloud, along with a 30 percent chance of showers. The high will reach 20°C, followed by cloudy periods Sunday night and a low of 8°C.
Wardrobe Recommendations
A light jacket or sweater is a good choice early this morning, especially with the damp air and temperatures near 10°C. By afternoon, layers will work best as temperatures climb toward 20°C.
Keep a rain jacket or compact umbrella handy today, particularly for the afternoon and early evening when showers and a thunderstorm risk are in the forecast. Despite the clouds, sunscreen and sunglasses are recommended because the UV index is high.
For Friday, lighter clothing should be comfortable during the day, but a jacket may be useful in the evening as cloud cover increases and temperatures fall.
Weather Trivia
Thunder Bay’s weather is strongly influenced by Lake Superior, especially in late spring and early summer. The lake’s colder waters can moderate temperatures, help create cool mornings, and sometimes influence where showers and clouds develop around the city.
Overview: Thunder Bay weather for June 18, 2026: mostly cloudy and humid near 10°C this morning, with a 60 percent chance of afternoon showers, thunderstorm risk, and a high of 20°C.
