The average long-term U.S. mortgage rate rose this week, pushing up borrowing costs for prospective homebuyers in the midst of the spring homebuying season.

The benchmark 30-year fixed rate mortgage rate rose to 6.3% from 6.23% last week, mortgage buyer Freddie Mac said Thursday. That’s still down from one year ago, when the rate averaged 6.76%.

The increase ends a three-week slide, bringing the average rate back to where it was two weeks ago.

Borrowing costs on 15-year fixed-rate mortgages, popular with homeowners refinancing their home loans, also moved higher this week. That average rate rose to 5.64% from 5.58% last week. A year ago, it was at 5.92%, Freddie Mac said.

Mortgage rates are influenced by several factors, from the Federal Reserve’s interest rate policy decisions to bond market investors’ expectations for the economy and inflation.

This week’s uptick in the average rate on a 30-year home loan follows a rise in the yield on U.S.…