Is severe [ie cold] winter weather related to global warming? - Washington Post

Weather isn't that simple, as it turns out. On average, the world is indeed getting warmer. (Even those skeptical about the human effect on Earth's climate don't dispute that fact, which is well established from year after year of upward-trending thermometer readings around the planet.) But global warming doesn't necessarily translate into warming everywhere, all the time.
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In other words, some melting ice and a moat of warmish water in the Arctic may be spawning the blasts of frigid air that keep pummeling us. How's that for a cold irony?