A Rainfall Warning has been issued for Windsor Essex and the surrounding regions.
The warning predicts as much as 70 millimetres or a little less than 3 inches of rain in the period from early Thursday to early Saturday.
Severe weather preparedness meteorologist Geoff Coulson says this is the latest in a string of similar systems that have saturated the ground.
He says the rain will be pretty steady starting early Thursday and tapering to showers Friday night.
Coulson says occasional downpours are possible during the storm event and why they've allowed for a big range of 40 to 70 mm of rainfall.
He says this is the latest storm moving in from Texas, but also the result of 2 forces colliding over our heads: "all of them have had excellent moisture feeds from the gulf of Mexico and this storm is no exception and we've notice the Jet Stream in general has been further south than normal this year leading to the cooler temperatures"
Coulson says the rain will ease off through the day Saturday, but temperatures will remain unseasonably cool until early next week.