Summer Warmth Friday, Sharp Cooldown Saturday
Thunder Bay – WEATHER – Friday, September 11, 2026 – Northwestern Ontario gets one more burst of summer-like warmth Friday before a cold front brings showers, possible thunderstorms and a dramatic temperature drop for the weekend.
Fort Frances reaches 26°C Friday, while Kenora, Dryden and Sioux Lookout climb to around 25°C and Armstrong reaches 27°C. By Saturday, many communities will be 10°C or more cooler, with highs mainly in the teens.
Today’s Weather Overview
Current Conditions
Early Friday, Kenora was sitting near 18°C under mostly cloudy skies, illustrating the mild air mass covering western Northwestern Ontario.
The main weather change arrives later Friday as clouds increase and showers develop. Thunderstorms are possible from Kenora through Fort Frances, Dryden, Ignace and Sioux Lookout.
Community Forecasts
Kenora
Friday: Sunny early, then a mix of sun and cloud with a 40 percent chance of late-afternoon showers and a thunderstorm risk. High 25°C, humidex 29.
Saturday: Much cooler with a mix of sun and cloud and a 40 percent chance of showers. High 15°C.
Sunday: Mix of sun and cloud with a 30 percent chance of showers. High 15°C.
Fort Frances
Friday: Sunny during the morning, then increasing cloud with a 40 percent chance of showers and a late-afternoon thunderstorm risk. High 26°C, humidex 31.
Saturday: Mix of sun and cloud with a 40 percent shower chance. High 17°C.
Sunday: Mix of sun and cloud with a 30 percent chance of showers. High 16°C.
Dryden and Vermilion Bay
Friday: Warm at 25°C, with clouds increasing and a 40 percent chance of late-day showers and thunderstorms. Southwest winds reach about 30 km/h.
Friday night remains unsettled with a 60 percent shower chance.
Saturday: Mix of sun and cloud with a 40 percent chance of showers. High 16°C.
Sunday: Still cool with a 30 percent chance of showers and a high near 15°C.
Ignace
Friday: Increasing cloud with a 40 percent chance of late-afternoon showers and a thunderstorm risk. High 24°C, humidex 28.
Saturday: Mix of sun and cloud with a 40 percent shower chance. High 16°C.
Sunday: Mix of sun and cloud, 30 percent chance of showers and a high of 15°C.
Red Lake
Friday: Mix of sun and cloud with a 30 percent chance of late-afternoon showers. Northwest winds develop near 20 km/h. High 24°C.
Saturday: Cloudy and considerably cooler with a 40 percent chance of showers. High just 13°C.
Sunday: Mix of sun and cloud with a 30 percent shower chance. High 14°C.
Sioux Lookout
Friday: Sunny during the morning, followed by increasing cloud and a 40 percent chance of late-afternoon showers and thunderstorms. High 25°C, humidex 29.
Saturday: Mix of sun and cloud with a 40 percent chance of showers. High 14°C.
Sunday: Mix of sun and cloud with a 30 percent chance of showers. High 14°C.
Armstrong
Armstrong will be the regional hot spot Friday.
Friday: Mainly sunny, then increasing cloud with a 30 percent chance of late-afternoon showers and a thunderstorm risk. High 27°C, humidex 31.
Friday night turns wet with showers, thunderstorms possible and 10 to 15 mm of rain.
Saturday: Mix of sun and cloud with a 40 percent chance of showers. High 17°C.
Sunday: Mix of sun and cloud with a 30 percent shower chance. High 15°C.
Pickle Lake
Friday: Mainly cloudy with a 30 percent chance of late-afternoon showers and a thunderstorm risk. Southwest winds near 30 km/h. High 23°C, humidex 26.
Saturday: Cloudy with a 40 percent chance of showers. High 14°C.
Sunday: Mix of sun and cloud with a 30 percent chance of showers. High 13°C.
Regional Three-Day Trend
Friday is the last truly warm day of this forecast. Highs range from 23°C at Pickle Lake to 27°C at Armstrong, with much of the region reaching the mid-20s. The approaching front brings increasing shower and thunderstorm chances late Friday and Friday night.
Saturday marks the sharp change. Red Lake falls from 24°C Friday to 13°C Saturday, Sioux Lookout drops from 25°C to 14°C, and Kenora falls from 25°C to 15°C.
Sunday remains cool but somewhat quieter, with highs generally between 13°C and 16°C and only scattered shower chances.
Highway and Travel Outlook
Friday afternoon and evening will be the most weather-sensitive travel period as showers and thunderstorms develop.
Heavy downpours could briefly reduce visibility on Highways 17, 71, 72, 105 and 599. Saturday remains showery but much cooler, while Sunday offers somewhat better travel conditions.
Motorists should check 511.on.ca before longer trips for the latest construction, incidents and road conditions.
Boating and Outdoor Outlook
Friday morning and early afternoon provide the best outdoor window, but boaters should watch the sky closely later in the day as thunderstorms develop.
Conditions turn significantly cooler Saturday on Lake of the Woods, Rainy Lake, Lac Seul, Wabigoon Lake and Red Lake.
Sunday remains cool enough that anyone spending extended time on the water should dress for fall rather than summer conditions.
Wardrobe Recommendations
Friday still supports summer clothing across most of Northwestern Ontario, although a light rain jacket should be close at hand.
Saturday requires a quick switch to sweaters, fleece and a wind-resistant outer layer. Overnight temperatures fall into the 4°C to 6°C range in several communities.
Sunday stays cool, making fall layers the better choice throughout the day.
Weather Trivia
Armstrong provides the clearest example of this weekend’s temperature swing.
The community reaches 27°C Friday, roughly eleven degrees above its normal September high of 16°C. Saturday falls to 17°C, and Sunday reaches only 15°C.
That rapid shift is classic September weather in Northwestern Ontario, where one passing cold front can replace summer-like warmth with autumn temperatures in less than 24 hours.
Source: Environment and Climate Change Canada forecasts available Friday morning, September 11, 2026. Forecasts can change as the cold front crosses the region.
Weather Summary
Northwestern Ontario weather for September 11-13, 2026: Summer-like warmth and thunderstorms Friday give way to a sharp Saturday cooldown and cool, showery Sunday conditions across Kenora, Fort Frances, Dryden, Red Lake, Sioux Lookout, Armstrong and Pickle Lake.
