WASHINGTON — Mortgage rates around the country dipped for a third week in a row, pushing 30-year mortgages to their lowest level since April.

Mortgage giant Freddie Mac said yesterday that 30-year, fixed-rate mortgages fell to 6.55 percent this week, down from 6.63 percent last week.

That was the lowest level for 30-year mortgages since they averaged 6.53 percent the week of April 20. Since that time, mortgages have been rising, hitting a more than four-year high of 6.80 percent the week of July 20.

Rates on 15-year, fixed-rate mortgages, a popular choice for refinancing, averaged 6.20 percent this week, down from 6.27 percent last week.

For one-year adjustable-rate mortgages, rates held steady at 5.69 percent, the same as last week, after having been at 5.78 percent the week of July 27.

Rates on five-year adjustable-rate mortgages fell to 6.21 percent this week, from 6.27 percent last week.