Hot temperatures prompted heat warnings in parts of Saskatchewan, Manitoba, Ontario, Quebec and adjacent provinces.
The rise came quickly after a prolonged warm spell in Ontario, its longest since 1934, with humidex making it feel hotter still.
Manitoba additionally broke a daily high mark record during the same stretch.
Metro Vancouver hit nearly 31 C early in the week earlier this week before rain starts Tuesday.
Authorities warned residents to limit exposure to the sun when danger peaks.