U.S. home sales perking up, but for how long?

A key measure of the nation's housing market picked up speed in February as sales of previously-owned homes climbed 1.2% and ran ahead of last year's pace for the fifth straight month.

That's according to the National Assn. of Realtors, which also said the median sales price of homes sold in February jumped at its fastest pace in 12 months, up 7.5% from a year ago to $202,600.

But those gains come as demand appears to be growing faster than the supply of homes for sale. If that keeps up, the market in many parts of the country could once again bump into the affordability challenges that have slowed sales in Southern California for more than a year now, warned Lawrence Yun, NAR's chief economist.

Inventory grew in February, as it typically does, but remains below levels seen a year ago. And at 4.6 months' worth of sales, the supply of homes on the market is well short of the six-month mark considered to represent a "balanced" market.

"Insufficient supply appears to be hampering prospective buyers in several areas of the country and is hiking prices to near unsuitable levels," he said. "Stronger price growth is a boon for homeowners looking to build additional equity, but it continues to be an obstacle for current buyers looking to close before rates rise."

Despite rough winter weather in much of the rest of the country, both sales volume and price growth was slowest in the West compared to a year ago.

NAR also said agents are seeing "tempered demand" from overseas buyers in popular international markets such as Southern California, because of the stronger value of the dollar.

Keep an eye on housing and real estate in Southern California. Follow me on Twitter at @bytimlogan