Mortgage rates: Nowhere to go but up?

• Charts below%3A Weekly mortgage rates and rates the past 30 years
• Historic low rates are history
• Regrets among buyers who didn%27t lock in lower rates

This week's sharp increase in mortgage rates — the biggest one-week leap in 26 years — won't likely be repeated, but a long era of historically low rates may be over.

Mortgage giant Freddie Mac said Thursday that the average 30-year fixed rate mortgage rose to 4.46%, the highest in almost two years, and up from under 4% the week before.

In the short run, this week's half a percentage point increase could push some home shoppers out of the market while spurring others to act before rates go higher, says John Burns, CEO of John Burns Real Estate Consulting.

Longer term, higher rates and more homes for sale could slow gains in home prices, whose rapid rise has spurred fears of another housing bubble.

In April, home prices were up 12.1% from a year ago and more than 20% in San Francisco, Phoenix, Las Vegas and Atlanta, Standard & Poor's Case-Shiller data show.

Higher interest rates will have a "small impact" on sales volume as well as prices, says Cameron Findlay, economist with Discover Home Loans. Gains of 20% year-over-year "are not sustainable or healthy," he adds.

Higher rates won't stop the housing market recovery, however, says Freddie Mac economist Frank Nothaft.

It has "enough momentum to continue," but sales volume and home price appreciation will be "less than what would've occurred," he says.

Nothaft expects rates to bounce between 4 3/8% and 4 5/8% through the end of the year. "The historic trough is history," he says.

The impact of the increase is already being observed in some places.

New customer volume was down 11% last weekend from the average of the previous three weekends at real estate brokerage Redfin, which tracks 19 major markets, says Glenn Kelman, Redfin CEO. Meanwhile, shoppers further along in the process rushed to close deals.

"We've had people calling us in tears. There were so many buyers at the outer limit of what they could afford," Kelman says.

The increases follow rising yields on the 10-year Treasury bond. They've climbed in the wake of Federal Reserve Chairman Ben Bernanke's comments last week that the Fed could start trimming its stimulus policies later this year if the economy continues to improve. Mortgage rates track the 10-year Treasury rate, which is at a two-year high.

Paul Diggle of Capital Economics expects 30-year rates of 4½% at year end, 5% next year and 5½ in 2015.

Average monthly rates have been below 4% since late 2011, Freddie Mac data show. But even at current levels, they're still low, having averaged 8.6% since 1971, Freddie Mac says.

At today's house prices and income levels, mortgage rates would have to be nearly 7% before the U.S. median-priced home would be unaffordable to a family making the median income in most parts of the country, a Freddie Mac analysis shows.

Higher rates will have the most impact on affordability in already high-cost areas, such as San Francisco south to San Diego and Washington, D.C., north to Boston, as well as in Seattle and Miami, Freddie Mac says.

Pending home sales rose in May to the highest level since late 2006, a potential sign that some fence-sitters jumped in to get ahead of higher rates, the National Association of Realtors said Thursday.