Toronto's bylaws require landlords to keep apartments at a minimum of 21°C from October 1 to May 15. Where the landlord provides air conditioning, it must run from June 1 to September 30 and keep units at or below 26°C; from June 2026, RentSafeTO buildings without in-unit cooling must keep a shared cool space at or below 26°C in summer.
The escalation ladder
Start in writing to the landlord and keep copies. If nothing happens, call 311 or file online — heat and vital-services complaints go to Municipal Licensing & Standards, who can inspect and issue orders (those orders appear in the City data this site uses). For ongoing problems, file a T6 (maintenance) or T2 (vital services) application at the LTB, where remedies include rent abatements. Never simply stop paying rent — that invites an L1.