The remnants of Hurricane Beryl drenched Ontario in heavy rain and was moving into Quebec as Environment Canada warned of possible “torrential” downpours lasting into Thursday.
The weather agency has issued rainfall warnings for the regions, saying amounts will be variable, but some areas may see up to 80 millimetres.
It says conditions should improve by Thursday, but there could be flash floods on roads and localized flooding.
The weather pattern comes as a blistering heat wave caused by a ridge of high pressure from northern California continues to slowly roll across Western Canada.
Environment Canada issued dozens of heat warnings across most of Saskatchewan on Tuesday, saying extreme temperatures are expected to persist the rest of the week before cooling slightly over the weekend.
Environment Canada meteorologist Jennifer Smith told a news conference Monday that scorching temperatures that have now set dozens of daily records in B.C. were likely to reach Manitoba today.
Smith said the ridge may reach the northwestern Ontario border before it moves south back into the United States.