U.S. mortgage rates creep up, but stay below 3%

30-year fixed-rate mortgage averages 2.99% for the week ending Aug. 20, up from 2.96% in the previous week and down from 3.55% a year ago, according to the Freddie Mac Primary Mortgage Market Survey.

"Purchase housing demand continues to accelerate, ultimately providing support to an economy that otherwise has stagnated," said Freddie Chief Economist Sam Khater.

15-year FRM averages 2.54% vs. 2.46% in the previous week and 3.03% a year ago.

5-year Treasury-indexed hybrid adjustable rate mortgage averages 2.91% vs. 2.90% in the prior week and 3.32% a year ago.