WASHINGTON – Turmoil in the stock market and the European debt crisis are making life easier for American homebuyers and families looking to refinance: Mortgage rates are inching closer to a record low.

The window of opportunity may close soon. Home loan rates will rise if investors grow more confident and shift money out of the safety of government bonds, which influence mortgage rates.

For now, though, rates are tantalizingly low. The average 30-year, fixed-rate loan sank to 4.78 percent this week, barely above the record of 4.71 percent set in December. And 15-year loans are at their lowest rates in two decades.

“Strike now,” suggested Greg McBride, senior financial analyst at Bankrate.com.

Some homeowners are doing just that. Applications to refinance surged this week to the highest level in seven months, the Mortgage Bankers Association said.

Anxiety over the European crisis has caused global investors to buy Treasury bonds, which they view as safer than other investments. Treasury yields have fallen as a result, taking mortgage rates down, too.

When the crisis eases, and especially if the American economic recovery stays on track, expect investors to move out of bonds and back into stocks. That would make mortgages more expensive.

“If the economy finally really shows sustained improvement, rates are definitely going to go up,” said Fred Chamberlin, a consultant with Alpine Mortgage Planning in Eugene, Ore.

He suggests that homeowners looking to refinance move fast and not hold out for even lower rates.

“If you want the bottom, the only way you’re going to know it is when you’ve missed it,” Chamberlin said.

As cheap as mortgages are these days, the number of loans being taken out to buy homes remains at its lowest point in more than 13 years.

One reason is that a special tax credit for homebuyers expired last month. Many people had rushed to sign contracts by then.

Another obstacle: trouble qualifying for a mortgage. Borrowers need solid credit and a down payment of at least 3.5 percent.