Mortgage interest rates fell slightly for the second consecutive week, according to Freddie Mac.

The 30-year fixed-rate mortgage averaged 4.15% for the week ending Feb. 16, down from last week when it averaged 4.17%. A year ago at this time, the 30-year fixed-rate mortgage averaged 3.65%.

"For the last 46 years, the 30-year mortgage rate has been almost perfectly correlated with the yield on the 10-year Treasury, but not this year. From Dec. 29, 2016, through today, the 30-year mortgage rate fell 17 basis points," said Sean Becketti, chief economist at Freddie Mac.

"In contrast, the 10-year Treasury yield began and ended the same period at 2.49%."

The 15-year fixed-rate mortgage averaged 3.35%, down from last week when it averaged 3.39%. A year ago at this time, the 15-year averaged 2.95%.

The five-year Treasury-indexed hybrid adjustable-rate mortgage averaged 3.18%, down from last week when it averaged 3.21%, while a year ago it averaged 2.85%.

"While we expect mortgage rates to fall into line with Treasury yields shortly, this just may be a year full of surprises," Becketti added.