Washington-area stocks, as represented by Johnston, Lemon & Co.'s index of 30 local corporation issues, appreciated in value last year by more than 29 percent.

Although the final quarter of the year was very weak (the index advanced overall only 1 percent in the final three months), the area stocks had generally outperformed the general stock market in the first nine months.

The year-to-year gain contrasts with a 15 percent increase for the Dow Jones average of 30 industrial blue chips traded on the New York Stock Exchange and a 26 percent gain by the Standard & Poor's 500-stock index.

However, both the American Stock Exchange index (up 41 percent) and the National Association of Securities Dealers index of over-the-counter stocks (up 34 percent) fared better over the year than the local 30 issues.

USAir Inc. was the largest percentage gainer among the 30 stocks in 1980, up 159 percent from $6.75 to $17.50, as the airline expanded into new markets under deregulation of the air industry.

Marriott Corp., which has launched a major expansion of hotel units, increased 86 percent to $32.75 from $17.62 1/2.

Overall, there were 23 gainers and seven losers among the 30 stocks for the year.

In the fourth quarter alone, all broad market indicators fared better than the Johnson, Lemon index. In part, this reflects the fact that local stocks had risen so rapidly earlier in the year, in advance of the broad national market increases.

USAir and Martin Marietta Corp. both rose 22.8 percent in the final period, bucking the general trend. Of the 30 stocks, 14 advanced in the recent three months. The biggest loser was Hechinger Co., off about 19 percent.