Environment Canada has issued a special weather statement for London-Middlesex ahead of a wall of rain.
According to the national weather agency, 25 to 50 mm of rainfall is expected on Friday and Saturday.
A series of low pressure systems from the Southern Plains states will be arriving in Southern Ontario to start the long weekend but should clear out by Sunday morning.
While the ground is generally no longer frozen, officials still say it will have a limited ability to absorb the rainfall and ponding of water is possible in low-lying areas.
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Meanwhile, the Upper Thames River Conservation Authority (UTRCA) has issued a water safety advisory. The conservation authority issued a statement Thursday afternoon, noting that with “watershed ground conditions generally saturated, runoff into waterways will be generated quickly.”
The UTRCA expects bodies of water to rise to near bank full conditions with flooding in low-lying, flood-prone areas.