A special air quality statement has been issued for Toronto and southern Ontario as wildfire smoke from the Prairies drifts to the region this evening. “Smoke is causing or expected to cause poor air quality and reduced visibility,” Environment Canada said in its advisory. “Air quality and visibility due to wildfire smoke can fluctuate over short distances and can vary considerably from hour to hour.” Environment Canada said air quality is expected to improve from north to south on Thursday. The national weather agency advises limiting time outdoors until the special air quality statement is lifted. Meanwhile, the heat warning that has been in effect since Saturday has lifted. It will be much cooler on Thursday, which is expected to be mainly cloudy with a high of 23 C and a 30 per cent chance of showers. Sunny conditions will persist with highs of 25 C, 27 C, and 29 C on Friday, Saturday and Sunday, respectively.