The rain and how much will impact flood conditions in Lake Muskoka and the Moon River, according to Muskoka Lakes Mayor Phil Harding.
Environment Canada says 20 to 35 mm of rain is expected Wednesday into Thursday, possibly mixing or starting as snow tonight.
A rainfall warning is effect for all Muskoka.
Harding says the water has risen 8 cm on Lake Muskoka and 16 cm on the Moon River but waters above Bracebridge and Huntsville are starting to slow, and if it wasn't for the rain, they might have hit a peak on Wednesday.
So far, the Township has not reported any evacuations, though there are some road closures.
Meantime, officials say water levels within Huntsville and Port Sydney Lakes are beginning to slowly drop but water levels will remain high over the next few days until the water works its way out of the river system.
In Bracebridge, floodwaters remain at historic levels, as 90 Canadian soldiers join others in bagging sand and assisting with evacuations, as necessary.
All water-side parks, access points and trails remain closed.
Mayor Graydon Smith said on Monday that the forecast rain will mean an extension of the flood event for all areas.