Budbreak is under way in the vineyards of northern California, the tiny and bright green leaves emerging boldly from canes signalling the start of another vintage. These bursting buds are chardonnay, basking in balmy spring sunshine Saturday at Madrona Vineyards on Apple Hill in El Dorado County, about 3,000 feet up the Sierra foothills.

Budbreak is expected in spring vineyards, of course, as vines stir from their winter dormancy. Winter this year, however, has itself been balmy, pushing the buds farther along than they usually are in late March. This is risky, especially in the foothills, where warmth and sunshine one day can yield to hard rain, hail, snow or frost the next. Indeed, thunder storms are forecast in the region today and tomorrow. If they materialize, they or subsequent freezing temperatures could knock these sensitive buds from their cane perches, dashing hopes that clusters of chardonnay could continue swell into fat and juicy bunches ready for harvest this late summer or fall.

That's why Madrona's Bush family, which has been farming wine grapes on Apple Hill since 1973, might look a little antsy and tired these next few days or weeks. Through the nights they will be monitoring the weather, temperatures especially, ready to spring into action and activate frost-protection measures in hopes of saving these precious buds. Their grape-growing neighbors will be on similar alert. And here we thought their lives were just a matter of tasting wine all day and then presiding over winemaker dinners in posh restaurants at night.