Weather for August 18, 2026: Showers, thunderstorms and gusty winds affect KI/Big Trout Lake, Sachigo Lake, Sandy Lake, Marten Falls/Ogoki Post and Wasaho Cree Nation/Fort Severn
A cool, unsettled Tuesday is taking shape across Ontario’s Far North. Kitchenuhmaykoosib Inninuwug/Big Trout Lake, Sachigo Lake, Sandy Lake, Marten Falls/Ogoki Post and Wasaho Cree Nation/Fort Severn are all dealing with some combination of showers, thunderstorms and gusty winds today.
The strongest winds are expected around KI and Sachigo Lake, where west winds may gust to 60 km/h. Sandy Lake and Ogoki Post face afternoon thunderstorm risks, while Fort Severn remains cloudy, damp and cool near Hudson Bay. Temperatures are running below normal in several communities. Conditions gradually improve Wednesday, with Thursday offering the best opportunity for sunshine across much of the region.
Today’s Weather Overview
KI / Big Trout Lake — Kitchenuhmaykoosib Inninuwug
Current Conditions
At 5:00 AM CDT, Big Trout Lake Airport was reporting clear skies and 10.3°C. Humidity was 88 percent, with a barometric pressure of 100.3 kPa. West winds were already blowing at 21 km/h and gusting to 39 km/h, while visibility was 16 kilometres.
Clouds and showers become the main story as the morning continues. Environment Canada is calling for a few showers, with a risk of a thunderstorm this afternoon. West winds strengthen to 30 km/h gusting to 60, making this a particularly breezy day for anyone travelling by boat or spending time in exposed areas. The high reaches only 14°C, compared with a seasonal normal maximum of about 20°C. Tonight remains cloudy with a 40 percent chance of showers. Northwest winds gust to 50 km/h before easing ahead of a low of 6°C.
Sachigo Lake
Current Conditions
Environment Canada is using Big Trout Lake Airport observations for Sachigo Lake. At 5:00 AM CDT, the station reported clear skies and 10.3°C, humidity of 88 percent, pressure of 100.3 kPa, and west winds at 21 km/h gusting to 39 km/h.
Showers are expected through Tuesday, with a risk of a thunderstorm this afternoon. West winds increase to 30 km/h gusting to 60, and the high reaches just 14°C. Tonight will remain cloudy with a 40 percent chance of showers. Northwest winds at 30 km/h gusting to 50 ease later in the evening, with temperatures falling to 6°C.
Marten Falls / Ogoki Post
Current Conditions
Fog was the main concern at Ogoki Post early Tuesday. At 6:00 AM EDT, Ogoki Post Airport reported fog and 13.2°C, with humidity at 100 percent and pressure at 100.5 kPa. Winds were west-southwest at 8 km/h, but visibility had dropped sharply to just 600 metres.
The weather becomes increasingly unsettled through the day. There is a 40 percent chance of showers this morning, followed by a few showers beginning around noon. A thunderstorm is possible from late morning through the afternoon. West winds increase significantly to 30 km/h gusting to 50. The high will reach 19°C. Showers taper this evening, although there remains a 40 percent chance of additional showers and an early-evening thunderstorm risk. The overnight low is 8°C.
Sandy Lake
Current Conditions
Sandy Lake started Tuesday on the cool side. At 5:00 AM CDT, Sandy Lake Airport was reporting clear skies and 9.2°C. Humidity was 89 percent, barometric pressure was 100.8 kPa, and winds were from the west at 13 km/h. Visibility was 16 kilometres.
Despite the clear early start, showers are expected today with a risk of a thunderstorm this afternoon. West winds reach 30 km/h gusting to 50, while the high struggles to only 15°C. That is well below Sandy Lake’s normal mid-August high of about 21°C. Tonight stays cloudy with a 40 percent chance of showers. Northwest winds of 20 km/h gusting to 40 accompany an overnight low of only 6°C.
Wasaho Cree Nation / Fort Severn
Current Conditions
At 6:00 AM EDT, Fort Severn Airport was reporting cloudy skies and 9.8°C. Humidity was very high at 96 percent, barometric pressure was 100.0 kPa, and south-southwest winds were light at 9 km/h.
Cloudy conditions continue through Tuesday with a 60 percent chance of showers and a risk of an afternoon thunderstorm. Morning fog patches will dissipate, while winds become northerly at 20 km/h gusting to 40 near noon. The high reaches only 14°C. Tonight remains cloudy with a 30 percent chance of showers and a low of 8°C.
Tomorrow’s Forecast
Wednesday, August 19
KI / Big Trout Lake: Wednesday brings a mix of sun and cloud with a 40 percent chance of showers. Northwest winds develop at 20 km/h during the afternoon. The high reaches 16°C, followed by clear skies and an overnight low of 6°C.
Sachigo Lake: Conditions are nearly identical, with a mix of sun and cloud, a 40 percent chance of showers, northwest winds developing during the afternoon and a high of 16°C. Wednesday night clears with a low of 6°C.
Marten Falls/Ogoki Post: Wednesday stays cloudy with a 40 percent chance of showers. Northwest winds at 20 km/h will gust to 40. The high reaches 18°C, with a 30 percent chance of showers Wednesday night and a low of 7°C.
Sandy Lake: A mix of sun and cloud comes with a 40 percent chance of showers and a high of 17°C. Skies clear Wednesday night as temperatures fall back to 6°C.
Wasaho Cree Nation/Fort Severn: Wednesday begins cloudy with a 30 percent chance of morning showers before skies become partly sunny during the afternoon. Northwest winds increase to 20 km/h gusting to 40 late in the morning. The high is just 13°C, followed by clear skies and a chilly overnight low of 5°C.
Thursday, August 20
Thursday brings a significant improvement to most of the Far North.
KI and Sachigo Lake are forecast to be sunny with highs of 19°C. Sandy Lake will also be sunny and warmer, reaching 21°C.
Ogoki Post will see a mix of sun and cloud with a 30 percent chance of showers and a high of 20°C. Thursday night clears with a low of 7°C.
Fort Severn gets sunshine as well, although temperatures remain distinctly cool near Hudson Bay with a high of only 15°C. Thursday night becomes partly cloudy with a low of 6°C.
Friday, August 21
Friday brings a little more cloud and shower potential back into the forecast.
KI and Sachigo Lake reach 21°C under a mix of sun and cloud with a 30 percent chance of showers. Ogoki Post also reaches 21°C with a 30 percent shower risk. Sandy Lake is forecast to be cloudy with a 40 percent chance of showers and a high of 19°C.
Fort Severn stays considerably cooler, with cloudy skies and a high of just 14°C. Friday night remains cloudy with a low of 6°C.
Wardrobe Recommendations
This is a rain jacket and warm-layer day across the Far North. With temperatures staying in the mid-teens in KI, Sachigo Lake, Sandy Lake and Fort Severn, a fleece, hoodie or light insulated jacket will be more comfortable than typical mid-August clothing. A waterproof outer layer and sturdy footwear are also useful with showers widespread and thunderstorms possible.
For Marten Falls/Ogoki Post, rain protection is especially important as showers develop, while anyone travelling early should account for the very low visibility associated with morning fog. Gusts of 50 to 60 km/h across parts of the region also make a wind-resistant outer layer worthwhile.
Anyone travelling on the water should pay particular attention to the stronger winds today. Even where rain is intermittent, gusty west and northwest winds can make conditions noticeably rougher on exposed lakes.
Weather Trivia
Tuesday’s temperatures offer a good example of how quickly late-summer weather can cool across Ontario’s Far North. Environment Canada’s climate normals put the mid-August daytime maximum at about 20°C for KI/Big Trout Lake and Sachigo Lake, 21°C at Sandy Lake, 20°C at Ogoki Post, and just 17°C at Fort Severn.
That makes today’s 14°C forecast highs in KI and Sachigo Lake roughly six degrees below normal, while Sandy Lake’s 15°C is also about six degrees below its seasonal maximum. Fort Severn’s 14°C is cooler than normal but not nearly as unusual given the community’s location close to Hudson Bay.
Source: Environment and Climate Change Canada observations and forecasts issued early Tuesday, August 18, 2026. Conditions can change rapidly where thunderstorms, fog and gusty winds are involved.
