September 5, 2025: Thunder Bay Weekend Weather Forecast

THUNDER BAY – WEATHER – Thunder Bay is starting this Friday on a cool and mostly cloudy note, with light winds and the temperature hovering just below 5°C.

While there’s a chance of showers and breezy conditions today, the forecast brings encouraging news heading into the weekend: milder, sunnier, and more stable weather is on the horizon.

Today’s Overview

Current Conditions (As of 5:00 AM EDT)

• Temperature: 4.8°C

• Condition: Mostly Cloudy

• Dew Point: 3.3°C

• Humidity: 90%

• Wind: West 9 km/h (increasing later)

• Pressure: 99.7 kPa and falling

• Visibility: 24 km

Friday’s weather includes a mix of sun and cloud with a 40% chance of showers, especially during the afternoon. Winds will shift to the west, gusting up to 50 km/h before calming later in the evening. Expect a high of 12°C, with a UV index of 5 (moderate).

Weekend Forecast for Thunder Bay

Saturday, September 6

• Day: A mix of sun and cloud, slightly warmer than Friday.

• High: 14°C

• UV Index: 5 (Moderate)

• Night: Cloudy periods with a 30% chance of showers.

• Low: 6°C

Sunday, September 7

• Day: A similar pattern—a mix of sun and cloud, but overall more pleasant.

• High: 16°C

• Night: Cloudy periods

• Low: 5°C

Monday, September 8

• Day: Mild and mostly sunny—the warmest day in over a week.

• High: 20°C

• Night: Cloudy

• Low: 9°C

Wardrobe Recommendations

• Today: Layer up with a wind-resistant jacket and water-repellent outerwear. A hat or scarf won’t go amiss in the wind.

• Saturday/Sunday: Dress in layers for cooler mornings, with a light jacket or hoodie for daytime comfort.

• Monday: Break out your early fall favorites—long sleeves in the morning, but short sleeves may do by afternoon.

Weather Trivia

Did You Know?
Thunder Bay’s Kaministiquia River valley can act as a wind funnel, amplifying gusts in parts of the city. That’s why breezy fall days like today can feel much colder in exposed areas—even when temperatures aren’t that low!