A heat warning previously in effect for the City of Toronto and the GTA has been upgraded to an extreme heat warning for Monday.

According to Environment Canada, temperatures are expected to reach a high of 34 C and a UV index of 8 by the afternoon.

There is a 40 per cent chance of showers this afternoon and a 60 per cent chance of thunderstorms in the early evening. However, the high temperatures are expected to remain in the low to mid-thirties until after midnight on Monday.

With the current weather conditions, Environment Canada said there is a possibility “severe thunderstorms” with wind gusts or large hail could develop. The southwest winds this evening are expected to reach 50 kilometres an hour.

Wind and hail can cause damage to buildings and vehicles, Environment Canada warned. They said to take cover immediately if a storm approaches.

“The best dynamics for severe storms this afternoon and evening are north and east of Toronto. Toronto may see some showers or thundershowers late afternoon or early evening but they are not expected to be severe,” CP24 Meteorologist Bill Coulter said. “Active weather will die down considerably after 8 p.m. as the cold front moves east and cooler, drier air filters into the region.”

As of 4:15 p.m., Environment Canada changed the status from severe thunderstorm watch to severe thunderstorm warning for parts of southern Ontario. Barrie, Collingwood, Northern Peterborough County and Bancroft could all see hail and strong winds according to the statement.

Toronto Public Health said the heat poses a risk for infants and young children, people with illnesses, limited mobility and the homeless.

“During an extreme heat warning, the public is encouraged to call or visit family, friends and neighbours, especially isolated adults and seniors who are at great risk of suffering from heat-related illness, to make sure they are cool and drinking plenty of fluids,” a statement from Toronto’s medical officer of health reads.

In an effort to beat the heat, Toronto Public Health has released a list of available ‘cooling centres’ that are available for those without air conditioning.

Cooling centres across the GTA include shopping malls, libraries and community centres.

The statement also advises the public to attempt to reschedule outdoor activities for shaded areas or cooler parts of the day.

By Tuesday, temperatures climb back to a more comfortable 22 C with mostly clear skies.

Toronto Public Health has suggested these locations to cool down at:

Metro Hall -- 55 John St.

East York Civic Centre -- 850 Coxwell Avenue

North York Civic Centre -- 5100 Yonge Street

Driftwood Community Centre -- 4401 Jane Street

Etobicoke Civic Centre -- 399 The West Mall

McGregor Community Centre 2231 -- 2231 Lawrence Avenue East

Centennial Park Community Centre -- 1967 Ellsemere Road

Cooling centres are open 11 a.m. to 7 p.m.