A smog advisory has been lifted for Toronto, Hamilton and parts of the GTA following a day of hot, muggy weather, but a heat warning remains in effect.

A statement released by Environment Canada Sunday said Toronto and parts of southern Ontario could see deteriorating air quality due to the scorching temperatures today. The advisory was lifted at around 9:30 p.m.

Environment Canada said a high of 33 C was expected today but the temperature felt closer to 38 C with humidity.

Toronto's medical officer of health also issued a heat warning for the city Sunday.

In a news release sent out Sunday, the city's top health official said the heat warning is in effect until further notice.

"During a Heat Warning, the public is encouraged to call or visit family, friends and neighbours, especially isolated adults and seniors who are at greater risk of suffering from heat-related illness, to make sure they are cool and drinking plenty of fluids," a statement from David McKeown, the city's medical officer of health, reads.

"Other groups at risk include people with chronic illnesses, individuals with limited mobility or certain mental health illnesses, infants and young children, people on certain medications, and those who are homeless."

A heat warning issued by Environment Canada Saturday remains in effect for Toronto, Halton, Peel, York and Durham regions.

People are encouraged to drink plenty of water, stay in air-conditioned spaces and are reminded to wear loose, light-coloured, breathable clothing when outdoors.