F.B.
We're from NYC. In late November, you can expect it to be cold, in the 40s - 50s, and possibly rainy, and occassionally snowing. You'll want hats and scarves, mittens, warm socks, proper shoes, long sleeved tees, sweaters and a 2/3 layer coat (a fleece and windbreaker that can be worn together or separately).
Just got off a flight from Toronto and there was a family waiting on the customs line with kids about the same ages as yours. The kids did wonderfully. They stayed near mom & dad, waited patiently, didn't make a peep, and didn't whine.
Start playing "airport" with them so they know what to expect, and what you expect of them.
Good luck to you and yours,
F. B.