Take Florida. Two month's ago, Newt Gingrich was leading Romney by 25% in the polls. Last week, Mittens has a 20% lead over the Salamander in the same polls. Today, Newt leads Mitt again by better than 9%.
Entire decades can go by with less polling volatility. Nobody dare predict what the result of the actual election next week will be but I guarantee you if Florida held another vote in March the results would be completely different.