Wildfire smoke returns to Toronto this week with thunderstorms forecast for Wednesday

Wildfire smoke from western Ontario is drifting into Toronto again this week, bringing hazy but safe conditions Tuesday before giving way to thunderstorms and heavy downpours.

The Air Quality Index remains low Tuesday despite the visible smoke, so outdoor activities are safe. But the AQI is expected to rise slightly Wednesday as humidity builds. A northerly wind will help clear the smoke, leaving clearer skies by Friday.

Two rounds of thunderstorms are forecast for Toronto on Wednesday. The first will pass through between 9 and 11 a.m., with a break in the afternoon before a second round hits between 5 and 6 p.m. Both rounds may bring heavy downpours, hail, and strong winds — conditions forecasters say could change quickly and unexpectedly. The rest of the night Wednesday will be clear.

Thursday, Friday, and Saturday look clear with highs between 24 to 29 degrees Celsius. Mugginess and rain will return Sunday with afternoon showers and a humidex of 33.

Drivers should adjust for storm conditions Wednesday, and anyone planning to get out on the water is advised to reconsider — conditions can become dangerous rapidly. This is the third time this summer wildfire smoke has reached Toronto; as HighOnCity reported in July, the city's skyline cleared after earlier smoke events.