The Essex Region Conservation Authority has issued a Flood Watch for the area.
With moderate to heavy rain expected over the next 24 to 36 hours, and with already saturated ground flooding is expected.
Between 30 and 60 mm of rain is expected on top of up to 60 mm over the weekend.
ERCA Flood Management Coordinator Tim Byrne says the volume of rain over the weekend created the current situation.
"The entire region is a fully saturated state right now so any type of rainfall that we're going to receive in the next while will create standing water and the potential for shallow flooding to occur"
Byrne says thunderstorms are a real threat.
"In areas where we could be hit with isolated heavy downpours we could see measurable flooding in those areas. There's no way to forecast where that would hit but just about anywhere in the region is susceptible to standing water and potential for flooding"
He says there's nowhere for the water to go right now.
"We're seeing most watercourses, waterways, municipal drains, creeks are bank full many of our larger waterways are well up out of the channel and into the flood plain areas"
Byrne says because the waterways are so full, it's extremely dangerous to be on the banks because they are weakened and could collapse.