You have to be prepared for any situation that's for sure.
Words to live by. There's been a lot of good information here, specifically about wearing layers of clothing. A lot of the extras you can get when you arrive but depending on when you actually get to Edmonton, a couple layers can save you a lot of discomfort before you get to the shops. If your boyfriend is already in Edmonton, he should be able to give you some good advice on what you'll need and when.
I heartily agree with the carrying salt/sand, a blanket, spare clothes, a candle and some dry foods in a car but as others have said chains won't be necessary in the city: if its that bad, no one will be going anywhere. One thing to remember is that driving on snow and ice is a LOT different than on dry roads... but so is walking in the white stuff (and I do recommend walking or ETS on the first day of winter rather than driving because too many people forget the difference every year).
One other thing I will mention, that may or may not be applicable is furnaces. If you own/rent a house, make sure the filter is clean and the unit has been checked out, greased, etc in the past year or so. Air conditioning in Alberta is nice to have in the summer but furnaces in the winter are survival equipment.