Montreal and surrounding regions are under a smog warning

A smog warning is in effect in Montreal on March 14, 2025. (Scott Prouse / CTV News)

Montreal and some surrounding regions are under a smog warning on Friday morning.

Environment and Climate Change Canada said that “high concentrations of pollutants will give poor air quality this morning, especially in locales where emissions are higher.”

The warning extends throughout much of southwestern Quebec including the Montreal, Laval, Vaudreuil and the Valleyfield-Beauharnois regions.

The warnings come as temperatures are forecast to poke past 10 degrees Celsius on the weekend.

The mercury is forecast to hit nine degrees on Friday and hit 13 on Saturday.

“Smog especially affects asthmatic children and people with respiratory ailments or heart disease,” the warning reads. “It is therefore recommended that these individuals avoid intense physical activity outdoors until the smog warning is lifted.”

The warning adds that wood heating is the main source contributing to smog in winter, and residents should consult municipality bylines about wood-burning stoves or fireplaces.

In Montreal, it is prohibited to use a wood-burning stove or other appliance unless it emits fewer than 2.5 grams of particles per hour.

During smog warnings, even certified solid fuel-burning appliances are prohibited in Montreal and residents can be fined if caught.