NEBRASKA -- Heating bills are burning a bigger hole in American wallets. 

The National Energy Assistance Directors Association said the average cost of keeping a house warm this winter is about $1,200.

That's a 17% increase from last year. 

Analysts said surging prices for natural gas and electricity are the main factors. 

This comes as a "once in a generation" winter blast is blanketing much of the country. 

The National Weather Service said more than 100 million people are under winter weather and wind chill alerts. 

About one of every six U.S. families are behind on their utility bills.