Growers are anticipating the 2013 Napa Valley winegrape season will begin with substantial emergence of vines from a winter nap in the last week of March, just ahead of the start of last year's record crop, according to a major local trade group.

This event, known as bud break, is anticipated to come four days ahead of last year, which could point to an earlier harvest if a number of other vine and weather factors cooperate, according to Napa Valley Grapegrowers. Since fall, the rainfall tally is 26 inches, deemed a "normal" pace and about the same as last year's, according to three of the organization's directors --Paul Goldberg of Bettinelli Vineyards, Remi Cohen of Cliff Lede Vineyards and Amy Warnock of Orin Swift -- brought together in a Yountville vineyard Friday for a season preview.

More rain is expected this spring, following stretches of clear, warm weather this winter. Yet, the long-term forecast is a "hot" summer, a change from mild to cool temperatures in the past few years.

Other highlights from the briefing:Fifteen percent of Napa County's 45,800 acres of winegrapes are being replanted.High demand for the county's cabernet sauvignon grapes pushed average prices last year to more than $5,000 a ton, an increase of more than 8 percent from the 2011 average.