Local conservation authorities and municipal staff are keeping their eyes on flood-prone areas.
The mild temperatures are expected to continue through the day Thursday and into Friday. There is still a chance of rain Thursday afternoon and evening before the temperature drops below freezing on Friday.
In the Ausable Bayfield watershed, the snowpack has started to settle, reducing the capacity to absorb additional rainfall before running off. Watercourses will rise overnight and through the day Friday, with flows in the largest rivers not peaking until late Friday and into Saturday.
Flooding will be limited to traditional low-lying floodplain areas and some local roads. The risk of ice jamming is limited to the river mouth areas of Port Franks, Bayfield, and to a lesser extent Grand Bend.
Strong onshore winds forecast for Friday may push lake ice towards these river mouths, enhancing ice-jam potential and higher lake levels.
The Maitland Valley Conservation Authority is also warning of minor flooding in low-lying areas of the watershed, and bank full conditions for streams and rivers.
Ice jams are also possible in some sections of the Nile Mile and Maitland rivers, which could trigger minor flooding.
A flood watch has been issued for the entire Grand River watershed.
The Grand River Conservation Authority says there is a risk of minor flooding in low-lying areas. There is the potential for ice jams in areas such as Grand Valley and West Montrose.
The GRCA says all its major reservoirs are at low winter holding levels and have storage available to manage the runoff.