Under John Williams's baton, the Boston Pops recordings excel

In the heat of the summer, one's musical thoughts turn to something lighter than the standard symphonic fare. And that means one turns to the Boston Pops.

John Williams is slowly making his presence felt on the ensemble, as can be heard in several of his recordings with the orchestra for Philips records. A look at these releases can also serve to call the reader's attention to the PBS series ''Evening at Pops.''

Williams is very much on view on that series, as is the late Arthur Fiedler. Mr. Williams will host such artists as drummer Buddy Rich (Aug. 9), violinist Itzhak Perlman (Aug. 16), Bernadette Peters (Aug. 23), TV and Broadway star Nell Carter (Aug. 30) and diva Leontyne Price (Sept. 6). Mr. Fiedler is remembered on Aug. 2 with the now-classic performance by Ethel Merman. (Check local listings for specific dates and times.)

The Boston Pops recordings under Williams's baton have gotten better and better. The first release was devoted to his own music for the movies: ''Star Wars,'' ''The Empire Strikes Back,'' ''Superman,'' and ''Close Encounters'' It is an exciting album, particularly if you have seen any or all of the movies in question.

The ''Close Encounters'' suite includes the music written for the closing minutes of the ''Special Edition'' reissue of the film (Philips 9500 921). The orchestra sounds glorious here, the digital technique ensuring a clarity of reproduction that doesn't reduce the warm ambiance of Symphony Hall (something digital quite often saps from the recorded sound).

''Pops on the March'' (Philips 6302 082) is a shrewdly chosen selection of favorite marches which actually avoids Sousa altogether. Mr. Williams's music is represented by his ''Midway March. '' The rest of the repertoire is culled from Elgar (Fourth ''Pomp and Circumstance''), Walton (''Orb and Sceptre''), Gershwin (''Strike Up the Band''), Meredith Willson (''76 Trombones''), and others. It is a refreshingly different march album, and the usual Philips care in matters of engineering, sound, and quiet pressings gives the venture a classiness so many of the later Fiedler Pops albums were denied at RCA.

The most recent album is also the finest - ''Pops Around the World'' (Philips 6514 186) - despite the peculiar subtitle ''Digital Overtures'' (how can an overture be digital?). Williams assigns himself a task usually left to the likes of a Karajan or a Bernstein - seven overtures from all walks of symphonic life. Included are, in order of performance, Kabalevsky's ''Colas Breugnon,'' Suppe's ''Boccaccio,'' Auber's ''The Bronze Horse,'' Glinka's ''Russlan and Ludmilla,'' Williams ''The Cowboys,'' Rossini's ''L'Italiana in Algeri,'' and Bernstein's ''Candide.''

Each one receives a lively, engaging performance from Williams (the ''Candide'' is especially dazzling), who is growing well into the role of well-rounded conductor capable of differentiating between Rossini and Verdi, between Beethoven and Bernstein, as well as being an accompanist for countless musicians - both on TV and in the nightly Pops concerts in Boston.