I'm in Western New York, temps similar to Toronto.
I always fill up at the same busy station. Couple weeks ago I had difficulty starting, glow plugs seemed to be the culprit.
They all checked out OK
Bought CDC Diesel Dry at a local parts store, solved the problem. Possibly a little moisture in your fuel.
I use a lower radiator hose heater. See Diesel Giant
Wife or car is a tough question