An overnight streamer blanketed London in a fresh layer of snow, and it's not expected to let up until a deep freeze kicks in.

School buses were cancelled in the City of London and Middlesex County, though schools remained open. Buses were up and running in Elgin and Oxford Counties.

The London Transit Commission says city buses were running but were delayed were to be expected due to the conditions.

The City of London says plows, salters and sanders have been on the streets since 3 a.m. and are expected to continue into Thursday night.

Officials add that all main road have been cleared of the nearly 30 centimetres of snow that fell overnight.

Meanwhile Huron-Perth was also hit with snow squalls overnight causing some road closures and bus cancellations.

Snow squall watches and warning have been in effect for much of the day in London and surrounding counties, but are expected to end by Thursday evening after another 5 to 10 cm of snow has fallen in some areas.

With more than 200 collisions locally Wednesday morning, police are urging commuters to give themselves extra time and space and to go slow.

Frigid temperatures coming

A blast of extremely cold weather is expected to follow the snow this weekend, and the Middlesex-London Health Unit expects to issue a cold weather alert Friday.

A polar front is moving in Friday night accompanied by gusting winds that will likely drop temperatures below -15 C, with a wind chill around -30 C.

The health unit advises people to bundle up and dress appropriately for the weather if they plan to be outside.