Sales of new homes in the Washington area boomed in October to their highest monthly total in at least seven years because of a selling surge at suburban projects, a local housing specialist reported yesterday.

The District market, on the other hand, remained stagnant, with condominium sales actually weaker than a year ago, said Renay Regardie, president of Housing Data Reports.

HDR has monitored sales of new homes in the Washington area since 1976, and the 3,253 contracts reported in October for all categories of homes was the highest it has recorded in that time, Regardie said. The figure was more than double that of October 1981 and 49 percent higher than September's, she said.

The housing industry has been in its longest, deepest slump since the Depression, mainly because of skyrocketing interest rates. Rates started coming down dramatically in August, however, and an unusual autumn housing rebound has followed throughout the country.

Housing starts nationally were 31 percent higher than the dismal levels of October 1981, and building permits were up 60 percent over the year earlier, according to figures released this week by the Commerce Department. Preliminary reports by the National Association of Realtors indicate that resales made a significant improvement in October.

But the HDR figures are the first to show such a dramatic upturn in sales in the Washington suburbs. They represent contracts signed rather than sales completed, which would lag by a month or more. Regardie said the number of contract cancellations has dropped dramatically since the first of the year from the 18 to 22 percent range to 9 to 10 percent.

"Sales came roaring back in October," Regardie said. "This points sharply to the fact that the long-awaited recovery is under way."

The October figures are not an aberration, she said, because preliminary reports for November show continuing strength.

"There is every potential for 1983 to come close to 1979," a boom year in sales, she said. While October's 3,200 level cannot be sustained, HDR expects to see "consistent improvement," Regardie said.

Single-family homes and town houses led the October upswing. Sales in this category were up 148 percent in Maryland and 126 percent in Virginia over year-earlier levels. The District doesn't have enough new, single-family projects to make a representative comparison, she said.