The average rate on a 30-year mortgage loan dropped this week to a four-month low, a welcome decline in borrowing costs for prospective homebuyers grappling with the challenge of record-high home prices and a dearth of properties on the market.

The rate fell to 6.77% from 6.89% last week, mortgage buyer Freddie Mac said Thursday. A year ago, it averaged 6.78%.

Borrowing costs on 15-year fixed-rate mortgages, popular with homeowners refinancing their home loans, also fell this week, pulling the average rate down to 6.05% from 6.17% last week. A year ago, it averaged 6.06%, Freddie Mac said.

Mortgage rates are influenced by several factors, including how the bond market reacts to the Federal Reserve’s interest rate policy and the moves in the 10-year Treasury yield, which lenders use as a guide to pricing home loans.

After jumping to a 23-year high of 7.79% in October, the average rate on a 30-year mortgage has mostly hovered around 7% this year — more than double what it was just three years ago.

Rates have eased recently as signs of cooling inflation have heightened expectations that the Federal Reserve will cut its benchmark rate as early as September.

Elevated mortgage rates, which can add hundreds of dollars a month in costs for borrowers, have discouraged home shoppers this year, extending the nation’s housing slump into its third year.