Mortgage rates fell to new lows this week, according to several national surveys, pushing housing affordability levels to near-record highs. Freddie Mac's weekly national survey said that the 30-year fixed-rate mortgage averaged 3.79 percent for the week ending May 17, down slightly from 3.83 percent the previous week. The 15-year fixed-rate mortgage was down, too, falling to 3.04 percent. Bankrate.com, which surveys the top 10 banks and thrifts in the nation's biggest markets, also reported record-low rates, saying the new low was the fourth consecutive record.

Rates are dropping largely because investors are feeling skittish about the European debt crisis and are putting their money into stable investments such as U.S. Treasuries. Yields on those Treasuries tend to closely follow mortgage rates, and word on the street is that as long as uncertainty in Europe prevails, so too will low rates.

Low borrowing costs and the lowest home prices in nearly a decade are creating unprecedented opportunities for home buyers. As of the end of April -- so not factoring the latest record low rates, the Minneapolis Area Association of Realtor's housing affordability index for the Twin Cities metro stood at a near-peak 238, which means that the median household income in the area was 238 percent of what is necessary to qualify for the median-priced home under prevailing rates.

Low rates also mean that it's time to consider refinancing, though many homeowners aren't in a position to do that because they owe more than their house is worth. Or, they're having trouble getting qualified for the mortgage. The National Mortgage Bankers Association said that mortgage applications were up 9.2 percent for the week ending May 11, and that the refinance share of those apps increased to 74.9 percent of all applications from 72.1 percent the week before. With fixed-rate mortgages so low, applications for adjustable-rate mortages are falling.