From Environment Canada:

Warnings

Burlington - Oakville
5:01 AM EST Sunday 09 December 2012
Freezing rain warning for 
Burlington - Oakville issued

First significant bout of winter weather expected.

A low pressure system originating in Colorado will head towards the Lower Great Lakes today. Periods of snow will begin in the southwest later this morning reaching Niagara and the Greater Toronto area (gta) to Georgian Bay later this afternoon. A coating of a centimetre or two of snow is likely from Southern Lake Huron eastwards into the gta by early this evening before it transitions into freezing rain this evening followed by rain.

More significant snow is likely farther north towards Georgian Bay and across Eastern Ontario beginning this evening where 5 to locally 10 cm is likely. It is highly expected to change to freezing rain overnight and persist well into Monday. A few millimetres of freezing rain may glaze some areas across the warned regions.

Motorists are urged to exercise caution during this first widespread wintery mix of precipitation. Untreated roads and sidewalks may become slippery from an accumulation of snow and freezing rain.

There is a slight risk that regions along the Ottawa Valley including Ottawa may exceed 10 to 15 centimetres of snow with snowfall warning criteria being breached. Environment Canada is monitoring the development of this weather system closely and will upgrade the freezing rain warning to a winter storm warning if the snow becomes more significant. 

(Source: weatheroffice.gc.ca)