Sean, if you want to know that, you should have paid more attention in geography lessons at school. Although we are at the same latitude as places that get very chilly in the winter, the gulf stream keeps us supplied with warm sea currents and air from the warmer southern climes and we therefore stay nice and toasty (well, relatively toasty). That's also where jellied eels come from, except they're not jellied until after they get here.
Might all change if the global climate change theories are right though.