Brrr..this morning was -26C at my house, -27 at the airport. The thing about thermometers, errors are most often, if not all the time, on the positive side. You rarely get a thermometer that reads colder than it actually is.
Anyway to the week's weather:
Warming up this week.
Friday's system has fizzled to some degree on the models. It looks like the models were jumping to much energy on this system, thereby driving it north too soon. It now looks to be an all snow event for Ottawa with temps staying below zero C. It will start overnight Thursday in Southern Ontario. There may be a mix of precip type in the Niagara peninsula and SW Ont. For Ottawa, it's looking like about 5cm of snow on Friday.
The real deal will be on Sunday, where most models are in agreement about another system passing just south or over the lower Great Lakes. The Euro (map below) is the most gung-ho about this one and if this comes to pass, there won't be much happening on Sunday, anywhere in southern and eastern Ontario.
The rest of Christmas week looks somewhat colder than normal but not extreme.
24 hr snow total in inches, ending Sunday night.