A special weather statement has been issued for Windsor-Essex and Chatham-Kent because of substantial rain on the way.
Environment Canada Meteorologist Gerald Cheng says people should expect a lot of rain.
15 to 25 mm of rain is expected Saturday night into Sunday morning, or nearly an inch.
Ponding of water on streets with blocked storm drains is possible.
Cheng says they don't anticipate downpours.
"I think it will be a very steady rain and I don't see any downpours yet, we're not quite there at least at this time around. But certainly make sure that the drains are unblocked so that the water can flow"
In addition, Southwest winds will gust up to 70 or 80 km/h on Sunday and continue for much of the day.
The rain and wind are associated with a Colorado Low that will track through Northeastern Ontario.
Temperatures are expected to gradually warm up with a high on Thursday of 12C or 54F.