Far North Ontario weather for August 24, 2026: Sunny and warm in KI, Sachigo Lake, Ogoki, Sandy Lake and Fort Severn before showers and cooler weather arrive

Thunder Bay = Weather Desk – A warm late-August Monday is underway across Ontario’s Far North, with sunshine dominating from Kitchenuhmaykoosib Inninuwug/Big Trout Lake and Sachigo Lake through Marten Falls/Ogoki Post and north to Wasaho Cree Nation/Fort Severn.

Afternoon temperatures will reach 24°C to 26°C, well above seasonal values in some northern communities. Fort Severn is forecast to reach 26°C—about 10 degrees warmer than its normal daytime high for this period. Sandy Lake will also be warm, but clouds increase this afternoon ahead of showers and a possible thunderstorm overnight.

The warmer pattern continues Tuesday before showers become more widespread Wednesday. A much cooler air mass then pushes into the Far North Thursday.

Today’s Weather Overview

KI / Big Trout Lake — Kitchenuhmaykoosib Inninuwug

Current Conditions

At 7:00 AM CDT, Big Trout Lake Airport was reporting sunny skies and 13.3°C. Relative humidity was 81 percent, barometric pressure was 101.7 kPa, and winds were from the west-southwest at 9 km/h. Visibility was 16 kilometres.

Monday will stay sunny, with any early fog patches dissipating this morning. The temperature climbs rapidly to 25°C, with a humidex of 27. The UV index is 5, or moderate. Tonight will be clear with a low of 13°C.

This is a notably warm day for late August in KI. Environment Canada’s extended forecast lists a normal daytime high near 18°C for the Big Trout Lake-Sachigo Lake region.

Sachigo Lake

Current Conditions

Environment Canada is using observations from Big Trout Lake Airport for Sachigo Lake. At 7:00 AM CDT, skies were sunny with a temperature of 13.3°C, humidity at 81 percent, pressure at 101.7 kPa, and west-southwest winds at 9 km/h.

Sachigo Lake stays sunny today, although south winds develop at 20 km/h late this afternoon. The high reaches 25°C, with a humidex of 27 and a moderate UV index of 5.

Clouds increase early tonight, but precipitation is not expected in the immediate overnight forecast. The low will be 14°C.

Sandy Lake

Current Conditions

At 6:00 AM CDT, Sandy Lake Airport was reporting clear skies and 12.8°C. Humidity was 81 percent, barometric pressure was 101.7 kPa, and winds were light from the south at 4 km/h. Visibility was 16 kilometres.

Sandy Lake starts sunny before clouds increase this afternoon. The high reaches 24°C, with a humidex of 26 and a moderate UV index of 5.

The bigger weather change arrives tonight. Skies become cloudy with a 60 percent chance of showers overnight and a risk of a thunderstorm. The overnight low will be 14°C.

Anyone planning overnight travel, boating or time on the land should monitor conditions as thunderstorms become possible later tonight.

Marten Falls / Ogoki Post

Current Conditions

Ogoki Post had a crisp but sunny start to Monday. At 8:00 AM EDT, Ogoki Post Airport was reporting sunshine and 7.7°C.

Humidity was very high at 96 percent, barometric pressure was 101.7 kPa, and northwest winds were blowing at 9 km/h. Visibility was 16 kilometres.

Fog patches dissipate this morning, leaving a sunny Monday. Temperatures climb sharply from the cool morning reading to a high of 24°C, with a humidex of 26 and moderate UV index of 5.

Tonight remains clear, although fog patches may develop overnight. Temperatures fall to 9°C, making for another cool early-morning start Tuesday.

Wasaho Cree Nation / Fort Severn

Current Conditions

At 8:00 AM EDT, Fort Severn Airport was reporting mostly cloudy skies and 13.7°C. Humidity was 82 percent, pressure stood at 101.4 kPa, and winds were from the south at 15 km/h. Visibility was 16 kilometres.

Cloud cover will give way to a mainly sunny and unusually warm Monday. Southwest winds strengthen to 30 km/h, while the temperature climbs to 26°C. The humidex will make it feel closer to 29.

Tonight turns clear. Southwest winds around 30 km/h become light early this evening, with the temperature settling to 14°C.

For a community this close to Hudson Bay, 26°C is particularly warm this late in August.

Tomorrow’s Forecast

Tuesday, August 25

Tuesday remains warm across the region, but the weather pattern starts becoming more unsettled from west to east.

KI / Big Trout Lake: Sunshine gives way to increasing cloud during the afternoon. The high reaches 26°C, with a humidex of 29. Tuesday night brings cloudy periods, a 30 percent chance of showers and a low near 13°C to 14°C.

Sachigo Lake: Mainly cloudy and warm with a high of 25°C and humidex of 29. Tuesday night brings a 30 percent chance of showers and a low of 13°C.

Sandy Lake: Cloudy with a 70 percent chance of showers and a risk of thunderstorms. The high reaches 23°C, feeling closer to 28 with the humidex. Tuesday night remains cloudy with a 40 percent chance of showers and a low of 13°C.

Marten Falls/Ogoki Post: Sunny early before clouds increase during the afternoon. South winds develop at 20 km/h late in the day. The high reaches a warm 26°C, with a humidex of 28. Tuesday night carries a 30 percent shower chance and falls to about 14°C.

Wasaho Cree Nation/Fort Severn: Sunny skies give way to a mix of sun and cloud late in the morning. The high again reaches 26°C, with a humidex of 28. Tuesday night becomes cloudy with a 30 percent chance of showers and a low of 13°C.

Wednesday, August 26 — Showers Become More Widespread

Wednesday marks the beginning of a more unsettled and gradually cooler pattern.

KI and Sachigo Lake will see a mix of sun and cloud with a 40 percent chance of showers and highs near 23°C. Wednesday night remains unsettled with a 30 percent shower chance and lows around 8°C.

Sandy Lake reaches 24°C under a mix of sun and cloud with a 40 percent chance of showers. Wednesday night falls to 11°C with a 30 percent shower chance.

Marten Falls/Ogoki Post will be cloudy with a 40 percent chance of showers and a high near 23°C. The overnight low falls to 10°C, with showers remaining possible.

Fort Severn experiences a much more noticeable cool-down. Wednesday will be cloudy with a 40 percent chance of showers and a high of only 18°C, followed by a low of 8°C Wednesday night.

Thursday, August 27 — Sharp Cool-Down Across the North

Thursday will feel dramatically different from Monday and Tuesday.

KI and Sachigo Lake will be cloudy with a 30 percent chance of showers and highs near only 16°C. Thursday night falls to 6°C.

Sandy Lake sees a mix of sun and cloud with a 30 percent chance of showers. The high reaches 19°C, followed by an overnight low of 8°C.

Marten Falls/Ogoki Post will be cloudy with a 30 percent chance of showers and a high near 16°C. Thursday night falls to 7°C.

Fort Severn will be the cold spot, with cloudy skies, a 30 percent chance of showers and a daytime high of only 13°C. Thursday night falls to 6°C.

That represents a remarkable temperature swing at Fort Severn: from 26°C Monday and Tuesday to just 13°C Thursday.

Wardrobe Recommendations

Monday and Tuesday will feel more like midsummer than late August during the afternoon. T-shirts and lighter clothingwill be comfortable once temperatures climb into the mid-20s, while sunglasses and sunscreen remain useful with moderate to high UV levels.

Morning temperatures tell a different story, particularly at Ogoki Post where Monday began below 8°C. A hoodie, fleece or light jacket remains useful for early travel and evening activities.

For Sandy Lake, keep a water-resistant jacket available tonight and Tuesday because showers and thunderstorms are possible. Rain gear becomes more useful throughout the region Wednesday as shower chances expand.

By Thursday, warmer layers return to the front of the closet. Highs of only 13°C to 19°C and nighttime temperatures around 6°C to 8°C will make a fleece, hoodie or light insulated jacket a practical choice, especially for people working outdoors or travelling on the land.

Boaters should also pay attention to Fort Severn’s southwest wind today. Winds around 30 km/h can create noticeably rougher conditions on exposed water.

Weather Trivia

The warmth forecast across the Far North today is particularly impressive when compared with Environment Canada’s late-August normals.

The normal high for the Big Trout Lake-Sachigo Lake area is about 18°C, meaning today’s 25°C forecast is roughly 7 degrees above normal. Around the Fort Hope-Webequie region, which includes the Ogoki forecast area, the normal high is close to 19°C.

The biggest departure is at Fort Severn. Its normal daytime high for this period is only about 16°C, while today’s forecast calls for 26°C—approximately 10 degrees above normal. By Thursday, Fort Severn drops back to a forecast high of only 13°C, highlighting how quickly temperatures can change near Hudson Bay in late summer.

Source: Environment and Climate Change Canada observations and forecasts issued Monday morning, August 24, 2026. The Far Northern Ontario public forecast was issued at 5:30 AM EDT, with Sandy Lake’s local forecast issued at 4:30 AM CDT.