We're being told to expect widespread, prolonged freezing rain overnight and Wednesday.
Environment Canada issued a freezing rain warning for Sarnia-Lambton, London-Middlesex, Chatham-Kent, and Windsor-Essex Tuesday morning.
Meteorologist Ryan Rozinskis said freezing rain will start after midnight.
"It could be around 12 hours or possibly even more of freezing rain through the area," said Rozinskis. "Now we're not looking at it falling heavily, however, the length of this freezing rain event is the main concern as it could allow surfaces, especially untreated surfaces, to become ice covered making travel difficult. We could see build up on utility lines and tree branches breaking with the weight of the ice."
The swath of freezing rain and ice pellets will gradually move east into the Greater Toronto Area by early afternoon Wednesday and last for several hours.
Motorists should be ready to adjust to changing driving conditions, and pedestrians are urged to take extra care.
Rozinskis said things will warm up on Thursday, before a return to unseasonably cold daytime temperatures for the weekend.
"We're looking at a fairly mild day Thursday with rain and around a high of 5 C (41 F) until a cold front from this system passes through Thursday night dropping temperatures and changing the rain over to snow as we head into Friday."