Far North Ontario weather for August 21, 2026: Showers, thunderstorms and strong winds affect KI/Big Trout Lake, Sachigo Lake, Sandy Lake and Fort Severn, while Marten Falls/Ogoki Post stays mainly sunny
Thunder Bay – WEATHER DESK – Ontario’s Far North is heading into an unsettled Friday, with showers and thunderstorms possible from Sandy Lake through Sachigo Lake and Kitchenuhmaykoosib Inninuwug/Big Trout Lake and north to Wasaho Cree Nation/Fort Severn. Stronger winds will develop as the day progresses, with gusts reaching 60 km/h at Sandy Lake and 50 km/h at Fort Severn.
Marten Falls/Ogoki Post is the exception today, enjoying a mainly sunny and warmer Friday before clouds and stronger northerly winds arrive tonight. Across the region, Saturday turns cooler before sunshine returns to several communities on Sunday.
Today’s Weather Overview
KI / Big Trout Lake — Kitchenuhmaykoosib Inninuwug
Current Conditions
At 6:57 AM CDT, Big Trout Lake Airport was reporting cloudy skies and 13.9°C. Humidity was 86 percent, barometric pressure was 101.2 kPa, and winds were from the west at 8 km/h. Visibility was 16 kilometres.
Clouds remain in place today, with a 60 percent chance of showers this afternoon and a risk of a thunderstorm. Southwest winds at 20 km/h ease this morning before strengthening again to 30 km/h this afternoon. The high reaches 20°C, a little above the normal August 21 maximum of 18°C.
Tonight remains cloudy with a 60 percent chance of showers and a risk of a thunderstorm early this evening. Winds eventually turn northwest at 20 km/h gusting to 40, and the temperature falls to 10°C.
Sachigo Lake
Current Conditions
Environment Canada is using observations from Big Trout Lake Airport for Sachigo Lake. At 6:57 AM CDT, the station was reporting 13.9°C under cloudy skies, humidity of 86 percent, pressure of 101.2 kPa, and west winds at 8 km/h.
Sachigo Lake will remain mainly cloudy with a 60 percent chance of showers and a risk of an afternoon thunderstorm. West winds increase to 20 km/h gusting to 40 this afternoon, with a high of 20°C.
Tonight stays cloudy with a 60 percent shower chance and an early-evening thunderstorm risk. Northwest winds gust to 40 km/h before easing for a time, with an overnight low of 10°C.
Sandy Lake
Current Conditions
At 6:00 AM CDT, Sandy Lake Airport was reporting cloudy skies and 15.6°C. Humidity was 67 percent, barometric pressure was 101.2 kPa, and west winds were blowing at 11 km/h. Visibility was 16 kilometres.
Friday becomes increasingly windy. Environment Canada forecasts mainly cloudy skies with a 60 percent chance of showers and a risk of a thunderstorm this afternoon. Northwest winds strengthen to 40 km/h gusting to 60, making Sandy Lake the windiest community in this roundup today. The high reaches 20°C.
Tonight stays mainly cloudy with a 30 percent chance of showers and an early-evening thunderstorm risk. Northwest winds continue around 30 km/h, with a low of 10°C.
Marten Falls / Ogoki Post
Current Conditions
Ogoki Post has the brightest start to Friday. At 7:00 AM EDT, Ogoki Post Airport was reporting sunny skies and 9.0°C. Humidity was 88 percent, pressure was 101.4 kPa, and south winds were light at 5 km/h.
Fog patches dissipate this morning, leaving a mainly sunny day. Ogoki reaches a pleasant 22°C, several degrees warmer than the seasonal normal high of 19°C. The UV index reaches 5, or moderate.
Clouds increase tonight, and north winds strengthen to 30 km/h before morning. The overnight low will be 12°C.
Wasaho Cree Nation / Fort Severn
Current Conditions
At 7:30 AM EDT, Fort Severn Airport was reporting cloudy skies and 12.0°C. Humidity was a damp 97 percent, pressure was 100.8 kPa, and south-southwest winds were blowing at 15 km/h. Visibility was 16 kilometres.
Fort Severn has an unsettled Friday ahead, with a 60 percent chance of showers and a risk of thunderstorms from late morning through the afternoon. Southwest winds increase to 30 km/h before turning northwest at 30 km/h and gusting to 50 km/h this afternoon. The high reaches 19°C.
Tonight remains cloudy with a 40 percent chance of evening showers. Winds become northerly at 30 km/h later tonight, with a low of 10°C.
Tomorrow’s Forecast
Saturday, August 22
Saturday brings a noticeable cool-down and continued cloud cover across much of the Far North.
KI / Big Trout Lake: Cloudy with a 30 percent chance of morning showers. North winds reach 30 km/h gusting to 50. High 18°C, followed by clearing and a chilly overnight low of 6°C.
Sachigo Lake: Cloudy with a 30 percent chance of morning showers. Northwest winds near 20 km/h ease during the afternoon. High 18°C. Saturday night clears with a low of 6°C.
Sandy Lake: An overcast Saturday with north winds strengthening to 30 km/h during the morning. High 19°C, followed by a clear night and low of 7°C.
Marten Falls/Ogoki Post: Cloudy with a 30 percent chance of showers. Northwest winds reach 20 km/h and gust to 40. The high is 18°C, followed by a 40 percent chance of showers Saturday night and a low of 9°C.
Wasaho Cree Nation/Fort Severn: Saturday will be cloudy, windy and much cooler. Northwest winds reach 20 km/h gusting to 40, while the high struggles to just 14°C. Saturday night remains cloudy with a low of 8°C.
Sunday, August 23
Sunday brings the best weather of the weekend to the western communities.
KI / Big Trout Lake and Sachigo Lake both turn sunny with highs of 20°C. Overnight temperatures fall to 10°C.
Sandy Lake also gets sunshine and warms to 22°C, with a clear Sunday night and a low of 10°C.
Marten Falls/Ogoki Post sees a mix of sun and cloud with a 30 percent chance of showers and a high of 19°C. Sunday night clears and becomes quite chilly at 6°C.
Fort Severn begins cloudy before conditions clear, with a high of only 16°C. Sunday night will be clear with a low of 9°C.
Monday, August 24
Monday currently looks warmer and brighter across much of the Far North.
KI and Sachigo Lake are forecast to be sunny and 23°C, while Ogoki Post will also be sunny with a high of 22°C. Sandy Lake reaches 22°C under a mix of sun and cloud with a 30 percent chance of showers.
The most dramatic warm-up comes at Fort Severn, where Environment Canada is forecasting sunshine and a high of 25°C—roughly nine degrees above the community’s normal daytime high for this point in August.
Wardrobe Recommendations
Friday is a rain-shell and windbreaker day for KI, Sachigo Lake, Sandy Lake and Fort Severn. Waterproof footwear will also be useful where showers develop, particularly for people spending extended periods outdoors.
Sandy Lake residents should plan for especially strong winds this afternoon, with gusts reaching 60 km/h. At Fort Severn, gusts to 50 km/h and possible thunderstorms make a wind-resistant waterproof outer layer the best choice.
Ogoki Post will be warmer and sunnier, so lighter clothing will work this afternoon, although the morning begins at only 9°C. A light jacket or sweater will be useful early in the day.
For Saturday and Sunday mornings, hoodies, fleeces and light insulated jackets are worthwhile. Overnight temperatures drop to only 6°C at KI, Sachigo Lake and Ogoki Post, and 7°C at Sandy Lake.
Anyone travelling by boat should pay close attention to rapidly changing conditions Friday. Thunderstorms combined with strong wind shifts can make exposed lakes considerably rougher in a short period.
Weather Trivia
The seasonal temperature differences across Ontario’s Far North become increasingly noticeable in late August. Environment Canada’s normals for August 21 list daytime highs of about 20°C at Sandy Lake, 19°C at Ogoki Post, 18°C at KI/Big Trout Lake and Sachigo Lake, and only 16°C at Fort Severn.
Fort Severn’s cooler normal reflects its location near Hudson Bay. That makes Monday’s forecast high of 25°Cparticularly noteworthy—about 9°C above the seasonal normal.
Source: Environment and Climate Change Canada observations and forecasts issued early Friday, August 21, 2026. Forecast conditions can change quickly where thunderstorms and strong winds are involved.
