A DAY WITHOUT SUNSHINE. By Les Whitten. Atheneum. 320 pp. $14.95.

THIS HAS BEEN a vintage year for thrillers about wine. Dick Francis' Proof has been humming along on the best-seller lists for some months, and now we have Les Whitten's A Day Without Sunshine, which is every bit as suspenseful and compelling, and from a wine- lover's point of view, more sophisticated and knowledgeable. If the Francis book is a tasty vin de pays, Whitten's is a classified Bordeaux from a good year.

Whitten plunges more deeply than Francis into wine history and chemistry and takes his hero -- a retired Pulitzer Prize-winning newsman and amateur Maryland winemaker -- to more parts of the globe in spinning out his plot. The main difference between the two books, though, lies in Whitten's lush cast of characters and his ingenious -- not to say outlandish -- plot.

A wine cartel, masterminded by a kinky and aristocratic London lawyer named Robert St. Gage, is buying up large tracts of vineyard land in Europe and is making nefarious deals with South American and North African growers. The object of the exercise is obviously to gain a corner on the world wine market. But what about that overflowing wine lake out in sunny California? St. Gage and his cohorts are making no moves in that direction, which is very suspicious and bodes ill for Napa, Sonoma and Mendocino. You just know that these villains will stop at nothing.

Enter Baroness Bethany von Mohrwald, in her late thirties, blond and beautiful. She and her philandering husband have scorned the cartel's bid for their ancient Austrian Schloss and have dark suspicions about what is afoot. At first they hire retired Inspector Jerome Wheatley-Smith, once Scotland Yard's expert on wine fraud, but he meets a quick and nasty end in the Napa. They then turn to Aubrey Warder, the Maryland man. He is loath to leave his grapes, but Wheatley-Smith was a pal and he grudgingly undertakes the case.

From that point, it's all hither and yon, hither and yon. California, Algeria, Portugal, Germany, a smashing wine auction at the Shoreham Hotel in Washington and the laboratory of a diabolical, anti-semitic wine chemist in a Paris townhouse . And has he got a surprise up his sleeve for the Californians! The cast of no-goods like the chemist is one of the most entertaining aspects of the book. Verisimilitude be hanged, there are oodles of them. In addition to St. Gage, who has a thing about armor and a lustful eye for the Baroness Bethany, they include -- to name a few -- Pierce Tobb (a former surfer who likes to invent bizarre ways of killing people), William Carnavan Bridesey (a Colonel Blimpish wine merchant -- a tiny streak of decency here) and my favorite, the Witwe (Widow) Pfferuhle, an American-hating German vineyard owner who for some reason reminds me of the wicked queen in Snow White .

There is in fact a cartoonlike quality about many of the characters. Nonetheless, Whitten (who was himself a newspaper man for 30 years and an associate of Jack Anderson), does manage to make the reader care about Warder and Bethany. He is able to make their relationship both sexy and sensible, no mean feat. But it is the helter-skelter pace and exotic locales, convincingly evoked, that put Whitten's book a cut above the normal thriller. For wine-lovers, the information conveyed is a pleasant bonus, like a small glass of Beaumes de Venise after a satisfying meal.