How long will it last? Minimal improvement in Ontario's air quality Thursday
Wildfire smoke will continue moving south across Ontario on Thursday, leading to poor air quality and increased health risks
Ontario faced some of the world's most hazardous air quality on Wednesday as wildfire smoke blanketed the region. At its worst, Toronto ranked first globally for poor air quality as conditions worsened throughout the day.
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Southern Ontario will see very poor air quality continue on Thursday as smoke persists in the region. Health officials advise to limit any time spent outdoors.
Air quality remains poor across southern Ontario Thursday
An outbreak of wildfires earlier this week in northern Ontario continues to fuel intense fire activity.
Air quality across the Greater Toronto Area (GTA) will see minimal improvement Thursday compared to Wednesday, remaining within the high-risk category.
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The thickest smoke plume will drift farther south, significantly affecting areas like London, Sarnia, and Windsor.
A wind shift from northwest to northeast will help improve air quality in eastern Ontario. Cities like Kingston, Peterborough, Belleville, and the Ottawa Valley may see slightly better conditions by Thursday evening, but most areas will still sit in the moderate range, with the easternmost regions improving to the low-risk category.
Smoke is expected to linger aloft for several days.
Rainfall outlook and smoke impact:
Northern Ontario could see some relief as 10–20 mm of rain, with isolated pockets of 15–30 mm west of Thunder Bay, is forecast from Thursday afternoon through Sunday. However, this is unlikely to eliminate fires or smoke.
Southern Ontario may also see rain and thunderstorms Friday evening into Saturday, though smoke could reduce precipitation intensity.
Uncertainty for air quality improvement:
The timing for clean air to return remains uncertain for southwestern Ontario.
Persistent northwesterly winds could continue to bring smoke into the weekend as new fires grow.
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Health and visibility impacts:
Smoke at low atmospheric levels raises health risks
Increased discomfort for individuals with respiratory conditions
Hazy skies and the smell of campfire
Red sunrises and sunsets
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Limiting outdoor activity is advised in affected areas.