In general, vintages matter less in California than they do in Europe. The state’s benevolent, fairly uniform climate means that California wines are, for the most part, dependably good year after year. This doesn’t mean that a producer’s wines taste the same every year or that you’ll like every vintage of every wine equally well. The point is simply that truly miserable vintages are not something most California wine drinkers have to worry about coming across.
Unlike many wine regions in the old World, California’s wine regions are usually threatened neither by rain during the harvest (potentially water logging or rotting the grapes), nor by severe frost during the spring (possibly killing the fragile young shoots), not by short cool summers (making full ripening virtually impossible). Nature tends to be on a Californian winemaker’s side.
When a California wine does seem to change a lot from one year to the next, it’s often for reasons other than climate. The producer may have lost an important source of grapes. Or, in the most ironic scenario of all, maybe the wine was so successful the producer decided to make more of it, necessitating buying grapes from other, less ideal vineyard areas to blend with the best grapes. (This very phenomenon resulted in a small ocean of mediocre merlot in the late 1990s.) Thus, in any given year, the character of some wines may deteriorate somewhat, though the reverse happens too, and every year some wines prove surprisingly good.