Environment Canada has issued a severe weather watch for most of southern Manitoba, including Winnipeg and all of the southwest area of the province.
Thunderstorms were expected to move into the Red River Valley and Interlake areas Monday afternoon before moving into the Whiteshell region in the evening.
Environment Canada meteorologist Dave Carlsen said Manitobans should be prepared for intense thunderstorms.
"With a fairly strong jetstream aloft, we can expect that some of these storms can intensify to severe levels. Hail maybe about … the size of golf balls and winds in excess of 90 kilometres an hour are the main threats."
He said that with high temperatures and humidity comes more rain.
Winnipeg suburbs of Fort Richmond and Whyte Ridge reported 30 to 40 millimetres of rain Sunday.
Swan River and the Interlake were expected to receive heavy rain Monday.
"Pretty much everywhere in Southern Manitoba it's kind of, turn off the taps please, because we've had so much rain," Carlsen said. "Yesterday alone, most areas south of the Trans-Canada got 20 to 30 millimetres."