WASHINGTON — Rates on 30-year mortgages fell for a third straight week, dropping to the lowest level since mid-July.

Freddie Mac, the mortgage company, reported yesterday that 30-year, fixed-rate mortgages dipped to 6.35 percent this week, down from 6.40 percent, the previous week. It marked the third consecutive decline and left rates at the lowest level since July 17 when they stood at 6.26 percent.

The Freddie Mac survey showed other mortgage rates also declined this week.

Rates on 15-year, fixed-rate mortgages, a popular choice for refinancing, fell to 5.90 percent, down from 5.93 percent last week.

Rates on five-year, adjustable-rate mortgages averaged 5.97 percent this week, down from 6.03 percent last week.

One-year, adjustable-rate mortgages dropped to 5.15 percent, down from 5.33 percent last week.