Temperatures could reach minus 20 overnight this week

Environment Canada is forecasting a nighttime deep freeze the week before Christmas.

This week's forecast shows temperatures getting progressively colder approaching the weekend with Saturday's overnight forecast calling for an overnight low of -21 C.

Daytime temperatures this weekend are expected to remain brisk as well, with a high of -13 C.

It would be the first time temperatures reach below -20 C this season.

Tuesday's temperatures show a high of 4 C and a 30 per cent chance of showers. Overnight temperatures will dip down to a low of -2 C.

Overnight rain has caused some icy roads and sidewalks this morning. Several school bus routes in the Ottawa Valley have been cancelled.

Snow could return on Wednesday with periods of snow forecasted early in the afternoon. About 2 centimetres of snowfall is expected.

A 40 per cent chance of flurries is expected overnight. Low of -9 C.

Thursday shows a chance of flurries with temperatures reaching -16 C in the evening.

Conditions are expected to remain clear this weekend.