The historically low mortgage rates borrowers have been enjoying won't last forever. But they will likely remain at or near rock-bottom at least until the end of the year, mortgage experts say.

While the trend can shift direction at any moment, many industry observers say they don't expect a significant jump in rates this year.

"Going into the next quarter, I don't think we will see much movement with rates," says Rob Nunziata, president of FBC Mortgage in Orlando, Fla. "However, if the economy starts picking up, I think we could see a slight bump up."

But it's unlikely the economy will improve before the year's end, he says. There are more than 14 million people unemployed, and housing markets remain sluggish in most areas.

"With the economy the way it is and problems surrounding the housing, I think it is very likely that rates will remain low through the end of the year," says Ron Peltier, chairman and CEO of HomeServices of America, a real estate brokerage in Minneapolis.

The latest forecast by the Mortgage Bankers Association estimates the average rate on the 30-year fixed-rate mortgage will be about 4.5 percent in the fourth quarter.

"It would be hard to think rates could go any lower, but they are clearly not going to be significantly elevated" in coming months, Peltier says.