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Smog Advisory

Smog Alert: December 5, 2022

Smog Watch

The Ministry of the Environment has issued a Smog Watch. For regional details see: Current Smog Watches.

Weather Summary: Issued on Tuesday, June 23, 2015

The main weather factors affecting air quality during the next several days include: Tuesday: -a cold front moving eastward over eastern Ontario during the morning is causing cloudiness and scattered precipitation over eastern regions and a high pressure ridge west of the Great Lakes region is causing partly clearing skies over southern, central and northern regions -winds are forecast to be west to northwesterly and gusty over most regions, except southwesterly during the morning over eastern regions ahead of the cold front, and temperatures are forecast to be cooler than seasonal values over most regions -air quality indices are forecast to be mainly in the good category in all forecast regions, mainly resulting from strong ventilation and dispersion conditions and upper level winds from the northwest across southern Ontario Wednesday: -the high pressure ridge is forecast to build over the Great Lakes region and to cause partly or mostly sunny skies and temperatures near seasonal values in most regions, except cooler in northern regions -winds are forecast to be westerly over most regions, except northwesterly over northern regions and southwesterly over some eastern regions -air quality indices are forecast to be in the good to moderate categories in southern Ontario, due to afternoon ozone generation, and generally in the good category elsewhere Air Quality Forecast: Air quality indices are forecast to be mainly in the good category across the province. Wednesday’s air quality indices are forecast to be in the good to moderate categories in southern Ontario and mainly in the good category elsewhere.

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Smog, comprised of ozone and/or PM2.5, is primarily a summer phenomenon, occurring mostly in southern Ontario; however, PM2.5 can elevate smog levels during all months of the year. For this reason, the ministry reports the AQI hourly, seven days a week; and continues to provide air quality forecasts daily.

Today's Air Quality Forecast
Today's Forecast

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