US mortgage rates climbed for a seventh consecutive week, rising to their highest level in nearly three years and deepening America's housing affordability problems.

Data released Wednesday by the Mortgage Bankers Association (MBA) showed the 30-year fixed mortgage rate rose 19 basis points to 7.49% in the week ending October 2, the highest since November 2023. Over the past three weeks, the rate has risen by a cumulative 0.5 percentage points, the fastest increase since early 2023.

Since the outbreak of the Iran war, energy costs and overall inflation have continued to climb, pushing up the yield on the 10-year US Treasury note, which has a major influence on mortgage rates and reached its highest level since 2002 on Monday.

Combined with home prices that remain elevated, mortgage rates have also curbed the growth momentum of both existing-home sales and new-home sales. The MBA's purchase index, which measures loan application volume, fell 2.1% to its lowest level in more than a year. The MBA's refinance index dropped 7.5%, extending a decline that began in mid-August.

The MBA survey has been conducted weekly since 1990, drawing on feedback from mortgage banks, commercial banks and savings institutions, with data covering more than 75% of all US retail home mortgage applications.