WASHINGTON — Rates on 30-year mortgages dropped this week to the lowest point in four months, providing some relief for people hoping to refinance their existing mortgages.

Freddie Mac, the mortgage company, reported yesterday that 30-year, fixed-rate mortgages averaged 6.31 percent this week, the lowest level since May 17, when 30-year mortgages averaged 6.21 percent. The rate had been 6.46 percent last week.

All mortgage products surveyed by Freddie Mac showed declines this week. Frank Nothaft, the company's chief economist, said this should provide help to homeowners who are hoping to refinance existing adjustable rate loans that are resetting from low introductory "teaser" rates.

An estimated 2 million such loans will reset over the next 18 months, raising fears about a wave of delinquencies as homeowners are unable to meet the new payments. Top Bush administration officials met with major mortgage servicing companies on Wednesday to urge them to extend as much assistance as possible to homeowners trying to avoid default by refinancing into mortgages they can afford.

Many economists believe the Federal Reserve will decide at its meeting Tuesday to cut a key interest rate in an effort to insulate the economy from recent turmoil in housing and financial markets.

Rates on 15-year fixed-rate mortgages averaged 5.97 percent this week, down from 6.15 percent last week. Rates on five-year adjustable rate mortgages averaged 6.17 percent, down from 6.32 percent, while one-year ARMs dropped to 5.66 percent, compared with 5.74 percent last week.