December will start seeming a little more seasonal in some parts of Ontario if a forecast 30-centimetre dump of snow comes later Friday as expected.

Environment Canada has issued a snow squall warning for areas east of Lake Huron and Georgian Bay. Forecasters are calling for 15 centimetres today, and another 15 tonight. Motorists are being warned to be ready for sudden dangerous winter driving conditions.

The agency predicts “snow squalls with whiteouts from heavy snow,” saying “lightning and thunder will also be possible.”

Niagara Falls, Welland and the southern Niagara Region are under a less-severe snow squall watch, with 15 centimetres of snow predicted for the worst-hit areas. Other parts of the Niagara Peninsula could get snow mixed with rain.