A major winter storm could bury Ottawa with 25 to 40 cm of snow as thousands of students and teachers return to class on Monday for the first time since the Christmas break.

"We are confident that there is going to be a significant snowfall," Environment Canada operational meteorologist Daniel Liota said.

Environment Canada has issued a winter storm watch for Ottawa, with 25 to 40 cm of snow expected Sunday night and Monday.

"Right now, the system is still on track to arrive early Monday morning," said Liota in an interview with CTV News Ottawa on Saturday. "The snow will really be heaviest kind of mid-morning into at least the early part of the afternoon before diminishing throughout the evening hours."

Environment Canada says Ottawa could see 2 to 5 cm of snow per hour Monday morning and afternoon.

The 25 to 40 cm of snow on Monday would set a record for greatest snowfall in Ottawa on Jan. 17. The current record is 11.7 cm of snow, set back in 1972.

Ottawa has only received 5 cm of snow in January, after 38.6 cm of snow in December.

A winter storm watch is also in effect for Kingston, Brockville, Leeds and Grenville, Cornwall-Morrisburg, Smiths Falls, Prescott and Russell, Renfrew-Pembroke and Barry's Bay.  All areas could see 25 to 40 cm of snow.

Liota says it is too soon to predict the exact snowfall and track for the storm.

"The concern that we're facing is the western edge of the snow, on the backside of the system, it's going to be a very sharp cut off – from rather significant amounts to minor amounts, even next to nothing," said Liota.  

"For eastern Ontario, it's seems a pretty safe bet that all areas will see a considerable snowfall – at least in the range of 15 plus centimetres."

The winter storm watch comes as an extreme cold warning remains in effect for Ottawa. A wind chill of minus 35 is expected overnight into Sunday.

Liota tells CTV News Ottawa the snow will provide a reprieve from the cold temperatures, but the cold "will return" on Tuesday and continue through the rest of the month.

"Unfortunately, the reprieve is not very long. It does look the cold returns later this week," said Liota.

"We do see some pretty strong signals that we're going to see at least another shot or two of very cold air before the end of this month. So it's going to be a very cold end to January."


The city of Ottawa says its equipment and operators will be ready for deployment as required when the snow starts to fall.

"After experiencing a few events with low accumulations, it seems like we are making up for lost time with this winter wallop," said the city on its website.

"The Roads and Parking Services Team is tracking a significant snowfall that is expected to reach Ottawa early on Monday, and we may need to declare this as a Significant Weather Event."

During a winter storm, the city will deploy plows to clear major roads, arterials and major collector roads once the snow starts falling.

After the last snowflake falls, the city says the snowclearing operations include:

  • Major roads, arterials and major collectors: Within four hours.  Roads will not be bare pavement during a storm.
  • Minor collector roads: Within six hours
  • Residential roads and lanes: Within 10 hours