In radio, the wake-'em and shake-'em early morning hours are prime time.

And in Washington for the last 25 years, there has hardly been any mystery about the leadership in the morning ratings: Frank Harden and Jackson Weaver of WMAL-AM (630) have dominated the market by ratings, by advertising, by longevity and by sheer personality.

Because the biggest audience of the day listens from 6 to 10 a.m., the performance of a morning show usually indicates a station's overall health. Often it is the morning lineup that gets a special boost from television advertising -- the current Greaseman ads from WWDC-FM (101.1), the utility ad from WMAL that mentions Harden and Weaver, and last year's pitch from WRQX-FM (107.3) for Jim Elliott and Scott Woodside illustrate this trend. "The morning drive at most radio stations will be responsible for 40 percent of the total revenues. The morning is the engine that pulls the rest of the day," says Jim Gallant, operations director at WMAL.

In recent years the local competition has heated up, and the once-inviolate 25-point share Harden & Weaver established in the first survey of Washington radio in 1965 has diminished. The number of stations has increased, the survey area is constantly growing and the dominance of AM radio has shifted. In the 1970s FM stations began specializing their formats and putting high-energy and polished talent in the morning drive. While appealing to a younger audience than Harden & Weaver, some Washington rivals tried the same team approach. Washington now has several sunrise duos, with the latest combo scheduled to start at WAVA-FM (105.1) next week.

Some local executives think listeners' growing preference for format over personality will only add to the morning frenzy. The public radio stations are also sharing in this mix of specialization: WETA-FM (90.9), which has a music and information show with Bill Cerri at that time, and WAMU-FM (88.5), which airs National Public Radio's "Morning Edition," each attract more than 75,000 listeners a week.

According to the last Arbitron Ratings survey, for fall 1984, the leaders in the 12-years-and-older category for the morning drive period are:

1. WMAL (630), 13.7. Harden and Weaver play standards and hits from the last four decades and do a host of character skits. Bud Steele and Karen Leggett do the news, Johnny Holliday the sports, Andy Parks traffic, Bob Ryan weather and Willard Scott calls in.

2. WKYS (93.9), 7.8. Donnie Simpson plays urban contemporary hits, new and old, and chats about current news. John Irving is the newsman.

3. WWDC (101.1), 6.8. Doug "Greaseman" Tracht plays rock 'n' roll, originates some outrageous skits and does the weather and traffic, as warranted.

4. WGAY-FM (99.5), 6.6. Jack Lynch plays beautiful music, reports the traffic and news.

5. WTOP-AM (1500), 5.5. Bill Thompson and Bill Torrey anchor the all-news show. Dave McConnell reports on Congress, Bob Dalton on business and Dave Statter and Bob Marbourg do the traffic.

6. WRQX-FM (107.3), 5.3. Jim Elliott and Scott Woodside play the new hits, Steve Palmer does the news and George Michael contributes sports twice in the show.

7. WMZQ-FM/AM (98.7/1390), 5.2. Jim London and Mary Ball play country sounds and entertain frequent guests. Evan Carl does the news and Gordon Barnes the weather.

8. WCLY-FM/AM (95.5), 4.9. Jeff Baker and David Burd play pop music, do skits on the famous of Washington and elsewhere, and stop for the news with Carol Thayer.

9. WHUR-FM (96.3), 4.5. Jesse Fax plays urban sounds, principally by black artists. Libby Lawson joins as co-chatter, reads the news and coanchors a daily issue interview at 9:30 a.m.

10. WLTT-FM (94.7), 3.9. Dave Arlington plays light rock, adds traffic and weather. Robert Garcia is the newsman.

To mark their silver milestone, Harden and Weaver will broadcast live from the Kennedy Center next Thursday from 6 to 10 a.m. Included among the greetings from figures in the sports, media and political worlds will be a message from Vice President Bush, who called the duo last June to "thank" them for saying he was trying to hide his 60th birthday and urging their listeners to call his office with congratulations.