The average rate on a 30-year mortgage in the U.S. rose for the sixth straight week, returning to its highest level since early July.

The rate ticked up to 6.79% from 6.72% last week, mortgage buyer Freddie Mac said Thursday. That's still down from a year ago, when the rate averaged 7.5%.

Borrowing costs on 15-year fixed-rate mortgages, popular with homeowners seeking to refinance their home loan to a lower rate, also edged higher this week. The average rate rose to 6% from 5.99% last week. A year ago, it averaged 6.81%, Freddie Mac said.

When mortgage rates increase they can add hundreds of dollars a month in costs for borrowers, reducing homebuyers' purchasing power at a time when home prices remain near all-time highs even though the housing market remains in a sales slump going back to 2022.

Mortgage rates are influenced by several factors, including the yield on U.S. 10-year Treasury bonds, which lenders use as a guide to price home loans. Bond yields have been rising following encouraging reports on inflation and the economy.

This week, bond yields surged on expectations that President-elect Donald Trump's plans for higher tariffs, lower tax rates and lighter regulation could lead to bigger economic growth, inflation and U.S. government debt.

The yield on the 10-year Treasury was at 4.36% at midday Thursday. It was at 3.62% as recently as mid-September.

The average rate on a 30-year home loan hasn't been this high since July 11, when it was 6.89%. In late September, the average rate got as low as 6.08% — its lowest level in two years.