Home mortage rates in the Washington area have surged dramatically, apparently heading back to the record levels of last spring when home buying ground to a halt because few families could afford the monthly payments.

Most local lenders now are demanding 14 percent interest on home loans -- and increase of 2 or 2 1/2 percentage points since July.

When interest rates go up from 12 to 14 percent, $100 a month is added to the payments on a $75,000 mortgage, pushing the cost from $898 a month to $998 a month. Over the life of a 30-year mortgage, the borrower pays an additional $36,000 in interest.

Last week, 63 percent of the local lenders raised their rates, according to a survey of banks and savings and loan associations by Peeke and Associates.

The average mortgage rate jumped a quarter of a point last week, said Victor Peeke, whose firm collects information on interest rates for the real estate industry.

Peeke found rates averaging between 13.8 and 13.9 percent, but rates have gone up again this week, passing 14 percent at many lenders. Further increase are expected next week.

Perpetual Federal Savings & Loan, the largest lender in the District of Columbia, has boosted its rate from 13 3/4 percent to 14 percent since last week, said Thomas Owen, Perpetual's president.

"I hope it isn't headed back to the peak we hit before," added Owen, whose savings association raised rates to 17 percent last March.

But Owen and others close to the mortgage market said yesterday they saw little to stop rates from continuing to climb.

Most mortgage lenders see considerable pressure for interest rates to continue to rise. They blame the resurgence of mortgage interest rates on the Federal Reserve Board's efforts to fight inflation and on the war between Iran and Iraq.

The war in the Middle East "is just an additional uncertainty," explained Sharon Stieber, director of economic analysis for the Federal Home Loan Mortgage Corp., known as Freddie Mac.

Fear that fighting between the rival Islamic nations might disrupt world oil supplies and cause economic repercussions "just adds another risk factor to the equation" when interest rates are determined, she said.

While the fighting continues in the desert, the Federal Reserve is battling inflation by trying to discourage borrowing, and its chief weapon is higher interest rates.

As a result, major banks yesterday raised the rate they charge their biggest and most creditworthy customers to 13 1/2 percent, half a point more than they were charging last week.

Mortgage rates are moving up in lock-step with the prime rate and other interest charges, said Peter Treadway, chief economist of the Federal National Mortgage Association, known as Fannie Mae.

Because most banks and savings associations are short of funds and uncertain about how to invest the money they have, most mortgage money is coming from the two agencies, Fannie Mae and Freddie Mae.

Rates at both of those agencies have gone up in the last two days, foreshadowing another round of mortgage cost increases next week.

Treadway said Fannie Mae this week offered money to lenders for conventional mortgages at 14.86 percent, up from a rate of 14.29 percent at its last offering two weeks ago.

Freddie Mac's rate was raised yesterday to 13.9 percent, but lenders must add three-eight of percentage point to cover the cost of servicing the loan. This results in a rate to homebuyers of 14 1/4 or higher.

Rates have been moving up steadily since June, when the current cycle hit bottom at between 11 1/2 percent and 11 3/4 percent. That is the lowest rate at which mortgages have been available in the past year, but it still higher than mortgage rates have ever been before.

After moving up steadily since the summer of 1979, rates peaked in March at 17 percent, then slowly worked their way down as the economy slipped into a recession.

Though the short-term outlook -- for the next month or so -- calls for higher rates, what will happen after that is all but impossible to predict.

"I've never seen a greater degree of uncertainty," said Treadway. "The tremendous swings we have been seeing were unheard of before."