Toronto has issued a heat alert, advising residents to take extra precautions because of the high temperatures. (Dwight Friesen/CBC)

A smog alert has been issued for much of southern, central and eastern Ontario — and Toronto has tacked on a heat alert, as well.

Environment Canada issued the smog advisory Sunday for a wide area that includes Toronto, Hamilton, Barrie, Peterborough, London, Sarnia, and Windsor. And an Environment Canada special weather advisory says the southern and central parts of the province can expect hot and increasingly humid weather to continue for several days.

With predicted highs in the low 30s, forecasters say it will feel more like the high 30s — maybe even 40 C — when the humidity is factored in.

A flow of polluted air from the United States is expected to combine with locally produced emissions, and Environment Canada predicts air quality for the region will be in the poor range as a result. Under a smog advisory, people are encouraged to do their part for air quality by parking their vehicles and taking public transit, walking or biking. People are also discouraged from working outside for long periods.

Toronto's medical officer of health issued a heat alert for the city amid the soaring temperatures. The heat wave that has enveloped the Greater Toronto Area is expected to stay in place most of the week.

People are advised to stay out of the sun, especially anyone with chronic health conditions, infants and the elderly. Experts also recommend drinking lots of water and finding air-conditioned spots to cool down.

Temperatures will be in the 30s in Windsor on Sunday and are expected to remain elevated throughout the week. In Ottawa it will be a little cooler Sunday, with the higher temperatures arriving Monday and staying for the rest of the week.

With files from The Canadian Press