Is that so different than current weather in Canada?
When I lived in Denmark the Copenhagen subway was shut down because of a bit of snowfall. 10 cm of snow brought Aalborg to a halt for days. Things we laugh at in Finland, but which they are simply not prepared for.
I'm afraid good old-fashioned -30C Siberian cold front would cause serious disruptions in Denmark and the southern half of Sweden (and possibly southern Norway -- not sure how used they are to cold weather, being blessed with ice-free coasts and all that). And without the North-Atlantic current to keep things nice and warm, it's just a matter of time before proper winters become a regular thing.
Besides short winter days, it's easy to forget how far north we are. Inland Russia, Canada, even europe at much lower latitudes have far more extreme weather.
At least here in the UK the plumbing isn't really designed for extended cold periods - meaning pipes often freeze when they come. If that happened every winter it wouldn't take very long for people to retrofit insulation and interior pipes.
Otherwise it's just a question of insulating buildings and having more infrastructure for snow. Snow often causes chaos because it comes so infrequently - there's very few snow ploughs, the trains don't have ploughs, pipes were routed without planning for freezing weather, people don't know how to drive in it, people don't have snow tires. All these things can be fixed in a few years of cold weather.