A wind chill warning has been issued for Waterloo Region and surrounding areas after a band of heavy snow and wind swept through southern Ontario Wednesday.

"Very cold north to northwest winds in the wake of the snow storm will draw in unseasonably cold air overnight," Environment Canada said in the warning issued Wednesday afternoon.

The weather agency predicted temperatures would dip to – 22 C in some areas overnight, which could have associated wind chill values near – 30. The average minimum temperature for this time of year is – 6 C.

Early in the day, southern Ontario was hit with a snow storm that resulted in at least 10 centimetres of snowfall in Waterloo Region.

The precipitation comes after a day of mild temperatures on Tuesday with minimal precipitation, which Environment Canada has characterized as a "springlike tease."

The snow started falling in earnest mid-morning, intensified in the mid-afternoon before ceasing in the early evening. The precipitation made for treacherous driving conditions, with Ontario Provincial Police warning motorists to slow down and drive defensively.

However, there were numerous crashes on southern Ontario highways throughout the day, including a 20-vehicle pileup on Highway 401 near Woodstock.

The wintry blast was caused by a low pressure system from Indiana that is moving through southern Ontario, bringing with it snow and wind across the Lower Great Lakes.