City health officials are warning Torontonians that they may issue an extreme heat alert if the city's already-sweltering temperatures soar any higher.

As the city trudges through a week-long heat wave, Environment Canada predicts Toronto will get more blistering hot weather throughout the week.

On Wednesday, temperatures are expected to get as hot as 32 degrees Celsius, while Thursday's forecast calls for highs of 36 C, with a humidex reading of 46 C.

Dr. David McKeown, Toronto's medical officer of health, is warning city residents that the high temperatures can be treacherous for many including isolated adults and seniors.

"I am asking everyone, including landlords, to check on those at risk," he said in a release on Tuesday.

An extreme heat alert is declared when the risk of heat-related death in the city is 50 per cent higher than what it would be on a typical day, according to Toronto Public Health.

If the extreme alert is issued, the city will open seven cooling centres and extend hours at nine pools.

Pool hours have already been extended to 11:45 p.m. at several city pools, a service that costs the city $6,000 a day.

The city has already spent several days under a heat alert, including Tuesday — the one day this week that had been considered a reprieve from an excessive heat wave.

Tuesday's heat alert declaration came just one day after Toronto cancelled a previous advisory that had lasted through the previous weekend.

After days of sticky weather, Toronto EMS reported receiving five to 10 per cent more calls than usual on Tuesday.

"We believe this is a result of the heat over the past number of days," said Toronto EMS Chief Paul Raftis.

During a heat alert, the public is encouraged to call or visit family and friends who are at a greater risk of suffering from heat-related illnesses, such as isolated adults and seniors.

It is also recommended residents drink extra water or fruit juice, wear light clothing and stay out of the sun.

When a heat alert is declared, those who need assistance or have heat-related inquiries may call the Canadian Red Cross Heat Information Line at 416-480-2615 between 9 a.m. and 9 p.m.

With a report from CTV's Naomi Parness