The Maitland Valley Conservation Authority says between 40 mm and 130 mm of rain has fallen across the Maitland and Nine Mile River watersheds overnight.
Small streams are reacting quickly and rising while larger rivers will continue to rise throughout the day on Friday and into Saturday.
Municipal officials are being asked to monitor roads for localized washouts and flooding due to the intense nature of the rainfall.
There were reports of flooding across Hwy. 21 south of Amberley Friday morning. Callers said there was fairly deep water across the road.
More flooding notes from drivers include the construction zone between Gowanstown and Palmerston. The road is down to one lane due to construction and the light is not working.
Also there is a flooded area near the post office in Harriston.