The average for a 30-year fixed jumbo mortgage was 4.48% last week, compared with 4.95% for a conventional loan.
Home shoppers' concerns about overpaying are giving way to fear of missing out.
As wealth flees cities for suburbs and exurbs, there aren't enough big homes to go around.
Costs for 30-year loans hit a more than two-year high of 3.69% last week.
The flight away from urban areas to healthier, safer and wealthier suburbs continues.
The average monthly payment on a $300,000 mortgage would be $1,301, up from $1,209 a year ago.
New York and other coastal cities are making a comeback as more workers return to the office.
Cracks are already appearing in the housing market, according to analyst Ivy Zelman.
The nation's housing market is a stark example of America's uneven economic recovery.
Rents on newly signed leases surged 17% in July when compared to what the prior tenant paid.