Borrowing money to buy a house just got more expensive. The average rate on a 30-year mortgage rose to 4.83%, Freddie Mac said Thursday. That's an increase of about two-thirds of a percentage point in five weeks.

The rate increase means monthly payments on new mortgages will jump. Five weeks ago, a buyer with a 30-year loan would have committed to payments of $487 a month. Now it's $526. That's an 8% price difference more than enough to give most shoppers pause.

Will costlier mortgages push already wobbly home prices lower? History offers some answers.

The recent rise in rates isn't nearly the sharpest in Freddie Mac's history. Over two years ended mid-1981, former Federal Reserve Chairman Paul Volcker raised the nation's core interest rate, the Fed funds rate, from a target of about 11% to one of 20% in an effort to combat high inflation. As a result, 30-year mortgage rates marched from 11% in June 1979 to over 16% by April 1980. The recent 8% increase in monthly payments over five weeks has nothing on the record five-week jump: more than 21% over the period ended March 28, 1980. Monthly payments per $100,000 soared to $1,347 from $1,109.

The effect on house prices? They rose more than 15% from 1979 to 1981.

Mortgage Rates and Home Prices

Inflation, to be sure, offset all of the increase and more. Subtract it, and house prices declined 9% over those two years. The nominal price increase, however, suggests that a whopper of a rate increase failed to trigger a selloff.

In 1987, following only a moderate uptick in inflation, the Fed gradual raised the core interest rate from 6% to 6.75% in late April and early May. The 30-year mortgage rate took a wilder rise, spiking nearly one and a half percentage points to 10.47% over five weeks ended May 1. Monthly payments rose 13%, to about $913 per $100,000 borrowed.

House prices soared 9% that year. Inflation averaged just 3.6%.

Mortgage payments rose nearly 11% over five weeks ended Aug. 8, 2003, to $621.58 per $100,000 borrowed. The increase signaled a broad economic recovery; growth in gross domestic product accelerated from 1.8% in 2002 to 3.6% in 2004. Immediately following the 2003 mortgage rate rise, prices shot 42% higher after inflation over three years.

It's unlikely that the recent mortgage rate increase foretells a rally of anywhere near that magnitude, but homeowners shouldn't assume that higher rates worsen the outlook for house prices. Current mortgage rates, after all, are still extraordinarily low. The 4.17% rate recorded five weeks ago is the lowest since at least 1970, when Freddie Mac was created. The average rate over the past four decades was close to 9%.

That's not to say that house prices won't dip for other reasons. Even before the recent rate increase, the Case-Shiller index of house prices fell 2% in the third quarter following a 4.7% rise in the second quarter.

Jobs, incomes and economic growth will likely decide what happens next, not a change in the 30-year mortgage rate.