National data show interest rates on mortgages continued their upward trend. Contract mortgage interest rates increased 0.25 percent from July to August, according to an index of new mortgage contracts.

According to the Federal Housing Finance Agency (FHFA), the National Average Contract Mortgage Rate for the Purchase of Previously Occupied Homes by Combined Lenders index was 4.26 percent for loans closed in late August. The index is calculated using FHFA’s Monthly Interest Rate Survey. The contract rate on the composite of all mortgage loans was 4.25 percent, up 25 basis points from 4.00 in July.

Interest rates are typically locked in 30-45 days before a loan is closed. Consequently, August data reflect market rates from mid-to-late July. The effective interest rate was 4.40 percent, up 28 basis points from 4.12 percent in July. The effective interest rate accounts for the addition of initial fees and charges over the life of the mortgage.

FHFA’s interest rate survey shows the average interest rate on conventional, 30-year, fixed-rate mortgages of $417,000 or less was 4.49 in August, an increase of 22 basis points. The average loan amount for all loans was $274,500 in August down $3,700 from $278,200 in July.

FHFA will release September index values October 29, 2013.