Affordability has been a frequently cited concern from prospective home buyers since 2014 began. Particularly in markets where available inventory is limited, rising home prices have scared off many house hunters, or at least caused them to temporarily step back. Given the many upfront costs that can't be skimped on, such as those that go toward title insurance or a home inspection, buyers are wise to seek out the most affordable long-term options.

But fears that rising interest rates may only compound affordability issues have not yet been realized. In fact, according to the latest data from the Zillow Mortgage Marketplace, rates are actually falling. For the first time since October 2013, the average interest on a 30-year-fixed rate mortgage was below 4 percent, dropping as low as 3.98 before settling in at 3.99 percent after the Memorial Day weekend. By comparison, 30-year FRMs averaged 4.05 percent a week earlier. The average rate on a 15-year fixed mortgage, meanwhile, was 2.98 percent, while the 5/1 adjustable-rate mortgage carried interest of 2.71 percent.

"Rates continued to drift lower last week, falling below the 4 percent threshold for the first time in months," said Erin Lantz, Zillow's vice president of mortgages. "In this holiday-shortened week, we expect rates will remain fairly stable unless economic data or Federal Reserve speakers surprise markets with meaningful insights into the health of the U.S. economy."

No better time to buy? 

Lantz was likely referring to the Fed's stimulus program, which has been reduced, or "tapered," by $10 billion each month since the start of 2014. Many analysts have assumed that as the central bank incrementally reduces its rate of bond buying, short-term interest rates will be subject to rise. That, however, has not yet proven true. Even after four consecutive tapering measures, mortgage rates remain relatively low by historical standards.

So, while hopeful homeowners don't necessarily need to keep a watchful eye on the Fed's maneuverings, it's worth bearing in mind that rates may not remain near their current lows forever. Capitalizing on an opportunity presented by the market's current conditions could significantly reduce the cost of homeownership on a monthly basis, and therefore over the life of a loan. As construction rates begin to pick back up and more inventory is generated, the combination of enhanced supply levels and still-manageable interest rates could lead to ideal conditions for buyers who are ready to make moves.