EXPLAINER: Stuck jet stream, La Nina causing weird weather

Winter has started out weird in the United States

America’s winter wonderland is starting out this season as anything but traditional.

The calendar says December but for much of the country temperatures beckon for sandals. Umbrellas, if not arks, are needed in the Pacific Northwest, while in the Rockies snow shovels are gathering cobwebs.

Meteorologists attribute the latest batch of record-shattering weather extremes to a stuck jet stream and the effects of a La Nina weather pattern from cooling waters in the equatorial Pacific.

It's still fall astronomically, but winter starts Dec. 1 for meteorologists. This year, no one told the weather that.