In a slightly more optimistic prognosis for homeowners or buyers, Frank E. Nothaft, the chief economist of Freddie Mac, wrote in an annual trend forecast on Dec. 6. that “while some rise in fixed-rates is expected, 30-year fixed-rate loans are likely to remain below 5 percent” throughout 2011.

With this year’s historically low rates, “there is a good chance that we have peaked, give or take a few basis points,” said HSH Associates, an independent publisher of mortgage and consumer loan information, in its most recent trends forecast. (One basis point is 0.01 percent.) According to Christopher J. Mayer, a senior vice dean and a professor of real estate, finance and economics at the Columbia University Business School, “The window of low rates could have left us.”

Mortgage rates typically track those of 10-year and 30-year Treasury and other government bonds. Yields, or interest rates, on those notes have been rising amid lender concerns that the White House’s deal with Congress on Dec. 7. to extend the Bush-era tax cuts and the Federal Reserve’s move in early November to buy back $600 billion in debt to stimulate economic growth will combine to fuel inflation and swell the budget deficit.

The 4.17 rate last month was the lowest since Freddie Mac began tracking rates in 1971 — as well as the lowest since World War II, according to Weiss Research, a financial analysis and publishing firm in Jupiter, Fla. The high point last year was 5.21 percent, in April.

So if you took out a 30-year fixed note for $400,000 at the recent 4.83 percent, you are paying $93 less per month than you would have in April — but nearly $157 more than you would have at the 4.17 percent benchmark.