Wild variations in the jet stream are pushing colder air south, where homes are poorly insulated, and scientists say this may be the tip of the iceberg.

ONE OF THE GREAT PLEASURES of living in places such as North Carolina and Northern Florida is the temperate climate. I've lived in both places, each time in a cinder-block ranch with no insulation, aluminum window frames and central air conditioning and baseboard electric radiators. The Florida home even had jalousied windows, little more than a translucent shutter system. But that was 20 years ago. And things are changing in a way that none of us could have anticipated. It's possible that much of the United States could be facing a "big chill."