From what i've heard and seen, 1974,75 ,1945-50, it seems to be a cyclical thing. And the whole thing might belong to a much larger cycle to. If you look at the ice cores they get from Greenland there is a definate pattern. Albeit one that spans many tens of thousands of years. Global warming just means we go into deep freeze earlier. Sounds wierd but temp peaks but then plummets, and the whole thing can happen within 10-50years.
Anyway up here it happens on a regular basis. In for another dose tonight so i think i'll stay indoors and keep warm,LOL.
Cheers