Toronto is under a severe thunderstorm watch after setting a new high-temperature mark for the year.

As of 3 p.m., the temperature in the city was 36.4 C, which broke the previous record of 36.3 C that was set earlier this summer, reported CBC meteorologist Michelle Leslie.

Environment Canada says that the temperature could still reach 37 C on Tuesday. The agency has also issued a severe thunderstorm watch for the city of Toronto and the surrounding regions of Durham, Halton, Peel and York.

Torontonians are warned of the development of thunderstorms that could bring "large hail, damaging winds or heavy rainfall."

The City of Toronto is also under an extreme heat alert, upgrading the previous warning issued late last week.

The extreme heat alert means city cooling centres are open for people who need them.

"During an extreme heat alert, 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," said a statement from the city.