Those rates are providing an incentive for buyers, along with falling home prices. They're tempting for refinancers, too.
Still, analysts say the combination isn't likely to lift the depressed housing industry or contribute much to the overall economy. In many metro areas, real estate is straining under the weight of foreclosures, higher down-payment requirements, tighter credit, still-high unemployment and buyers' expectations of even lower prices.
"If people aren't confident about the economy, about jobs and home prices, they certainly aren't going to sign up for the biggest purchase of their lives," said Greg McBride, a senior analyst at Bankrate.com.
But for those with jobs, money and creditworthiness, today's rates can be tantalizing.
This week, a qualified buyer could expect to finance a home over 30 years at an average fixed rate of 4.63 percent, according to mortgage buyer Freddie Mac. That's the lowest average rate in five months. In November, the rate hit a four-decade low of 4.17 percent.
The 15-year fixed mortgage, popular with refinancers, is down to 3.82 percent. That's also the lowest point since December.
Weak sales and a growing belief that prices have yet to hit bottom five years after the housing bubble burst have become a major obstacle for the economy. Homebuilding is down. Fewer first-time buyers are entering the market. The pace of home sales remains far below the level economists view as healthy.
But the biggest threat is foreclosures, said Mark Vitner, a senior economist at Wells Fargo. A wave of foreclosures is forcing down prices in most major U.S. cities.
About 3.7 million homeowners are at serious risk of losing their houses, according to the Mortgage Bankers Association. Foreclosures typically drag down the prices of nearby homes, putting even more homeowners in a financial bind.
More than a quarter of homeowners can't sell their homes because they owe more on their mortgage than their house is worth. And many would-be buyers are holding off on a purchase, mindful that prices might fall further.
"What good is a low rate if you're upside down on your mortgage?" said J. Philip Faranda, who runs a real estate firm in Westchester County, N.Y.
Even those who do feel ready to buy are having a harder time qualifying for a mortgage. The average credit score for a loan backed by Fannie Mae and Freddie Mac has jumped to 760, compared with 720 four years ago, according to the government-run mortgage buyers that back 90 percent of new loans. Fewer than half of American adults have credit scores as high as 760.
And banks are insisting on higher down payments. The median down payment rose to 22 percent last year in at least nine major U.S. cities, according to a survey by Zillow.com, a real estate data firm. That's up from 4 percent in 2006.
"Lenders are reluctant to hand out loans unless you can bring some skin to the deal, in the form of a bigger deposit," said Patrick Newport, U.S. economist for HIS Global Insight. "Until that changes, low mortgage rates aren't going to make that much of a difference. Credit is simply hard to get."
Home-loan financing has remained tight despite a wave of hiring, stronger consumer and business spending and a steadily rising economy. About 92 percent of banks say credit standards on mortgage loans have remained basically unchanged, according to the Federal Reserve's senior loan office opinion survey released last month. About 45 percent said demand for home loans has been moderately weaker.
"There aren't many buyers with deep enough pockets who can put 20 to 25 percent down," said Julie Longtin, a real estate agent with RE/MAX Cityside in Providence, R.I.
And only two-thirds of Americans view homeownership as a safe investment, down from 83 percent in 2003, according to a Fannie Mae survey this year. Few economists see home values rebounding this year.
"The concern is, 'Are values going to go up at this point, or go down or flatline?'" said Ben Coleman, broker-owner of Century 21 Hartford Properties in San Francisco. "I've seen where interest rates were dropping, and it's almost like a 'ho-hum.'"
The rate on the 30-year mortgage has spent most of the past year below 5 percent. Until last year, that would have been considered a bargain. This time, even those who could afford to buy will likely take a pass.
"What really may be the catalyst for buyers is when rates start moving back up," said Mark Zandi, chief economist at Moody's Analytics. "Rates are low and still seem to be falling, so there's no pressure now to pull the trigger."