BARRIE, ONT. -- Heavy rain on the way could spoil the long weekend.

Environment Canada has issued a rainfall warning for the areas of Parry Sound-Muskoka, Haliburton and Peterborough-Kawartha Lakes.

Heavy rain is expected to start early Sunday and last into the evening.

Affected communities could see between 40 and 60 mm of rain, and 75 mm locally is possible.

The weather agency cautions could translate into water pooling on roads, poor visibility, or flash floods.

Showers are again possible on Monday.