Hot weather is predicted across most of Ontario from Friday through Sunday, Environment Canada reports.
Toronto and Ottawa will see daily highs near 32 C each day, with overnight lows not falling under 19 C.
Humidity will drive humidex values to around 38 to 40 throughout afternoon hours, officials say.
Heat alerts continue in effect at the "excessive heat" level, particularly for vulnerable populations.
Residents are advised to stay well‑hydrated and reduce outdoor activity during peak heat.
Officials also recommend checking on senior relatives frequently.
Public cooling centres are open throughout for those in need.
Travelers should keep water bottles and wear light clothing.