Snow squalls and whiteout conditions continued to cause problems on the roads across southern Ontario Friday.
At about 12 pm, all eastbound lanes on Highway 401 were closed near Woodstock due to a 30-vehicle pile-up.
At the time of the crash, a thick band of snow was reported in the region, reducing visibility and creating dangerous conditions.
Police officials say any injuries are believed to be minor.
After two days of mild and even record breaking temperatures, winter made a comeback to the region on Thursday.
Temperatures took a rapid plunge, creating an icy and extremely hazardous morning commute.
At one point, Toronto police closed a portion of the Gardiner because of the slick and ice covered roads.
Officials say at least 150 collisions were reported between 6-10 am as a result of glare ice and people driving too fast.
Powerful winds and snow squalls also left drivers navigating through some dangerous whiteout conditions.
"Snow squalls are extremely unpredictable," says The Weather Network's Kasia Bodurka, who was in the thick of the storm on Thursday. "One moment you can have clear blue skies, and the next, thick, heavy bands of blowing snow."
There's the potential for more snow squalls to develop through the day on Friday and motorists are urged to adjust their driving habits accordingly.
Poor and fluctuating visibilities are expected in some areas along with rapid snow accumulation on untreated roads.
"It was pouring rain with thunderstorms just a few days ago and now we've got snow squalls, snow falling, strong winds and chilly conditions," says Dayna Vettese, a meteorologist at The Weather Network. "It's safe to say winter is definitely back."
Hamilton is expected to receive up to 5 cm of snow by Saturday morning.
Communities around Fort Eerie could start the weekend off with up to 20 cm of snow.