A Special Weather Statement remains in place for Windsor-Essex.
The statement was issued by Environment Canada on Tuesday and calls for the possibility of significant rainfall today.
Severe weather meteorologist Rob Kuhn says the region could see up to 25mm of rain by midnight.
"We're looking at a large low approaching from the southwest and it's got bands of showers spiralling around them," Kuhn said.
Kuhn says showers will be on and off today and throughout the evening.
"There's a slight chance of a thunderstorm late this afternoon into this evening, maybe a rumble or two of thunder with that."
He says there is a slight chance of a thunderstorm.
"The big thing though is the rain amounts," he continued. "They're not horrendous however they are certainly enough to make a difference. Again with the ground being partially frozen in some areas and still wet from the spring melt.
Kuhn says poorly drained areas may be subject to ponding of water, and adds there is also a chance of localized flooding in low-lying areas.
A Special Weather Statement is also in place for Chatham-Kent.