(NBCBayarea) - Bay Area winemakers have endured an array of weather challenges over the last year; a cool summer, early rains, lack of rain and now warm temperatures that have brought some vineyards prematurely to life. Livermore winemakers said signs of life among the vines are not necessarily a good thing, since early March also brings the possibility of frost. “The critical time for us with frost, is now,” said Mark Clarin, winemaker at McGrail Vineyards in Livermore. “For the next four or five weeks we’re going to pray to the warming gods.”