Ontario could be hit with heavy rainfall over the next few days by remnants of hurricane Katrina, the Canadian Hurricane Centre in Halifax said.

"It's mostly a rain event," said Steve Miller of the Hurricane Centre.

He predicted that at least 50 millimetres of warm rain could fall in the Toronto area as early as Wednesday, with more expected toward Kingston, Ont., and into Quebec later in the week.

However, David Phillips, senior climatologist at Environment Canada, said it's still not completely clear how the weakened Katrina will affect Canada.

"If it speeds up, we won't get nearly as much rain because it won't rain for as many hours," he told CTV Newsnet Tuesday.

He says the weather system has been edging eastward. "The more east it goes, the less likely we'll see precipitation in Ontario."

He predicted that southern Quebec should see some rain, as would New Brunswick on Thursday.

"But it will dry up before the (Rolling) Stones get going there on Saturday evening," Phillips said.

More than 80,000 people are expected to attend the outdoor Stones concert in Moncton, N.B., on Saturday. Concert organizers say the event will go ahead rain or shine.

Earlier Tuesday, Environment Canada forecaster Geoff Colson estimated that between 50 and 75 millimetres of rain could fall in the area around the Niagara Peninsula and along the St. Lawrence River.

Between 20 and 40 millimetres of rain could fall in areas north of the system, such as Toronto.

Katrina, which started out as a Category 5 storm just days ago, has since been downgraded to a tropical depression.

The hurricane slammed into the U.S. Gulf Coast on Monday, leaving a trail of death and destruction in Mississippi, Alabama and Louisiana.