A global analysis in fact shows just how connected the U.K. storms are to the rest of the world. That extreme cold weather over the United States and Canada is coinciding with the U.K. storms is not by chance. These are not local events happening in isolation, but rather storms associated with "major perturbations to the Pacific and North Atlantic jet streams driven, in part, by persistent rainfall over Indonesia and the tropical West Pacific," Dame Julia and her team at the Met Office reported.

The higher rainfall over Indonesia is itself tied to higher-than-normal ocean temperatures in that region. Looking at the weather patterns in December and January, the rainfall and perturbations to the jet stream would imply La Niña-like conditions. And while El Niño or its cold counterpart La Niña is usually the first suspect in ocean temperature and rainfall variations, the eastern Pacific showed no sign of either.