The 2010 growing season was one of the coolest in recent memory, which led to a much shorter than average growing season; for many vineyards this created serious challenges in getting fruit to ripen adequately. Additional difficulties were created by an abrupt heat spike in late September and subsequently the early heavy rains in some areas. This article focuses on the very unusual temperature conditions of the 2010 season, using as the basis for comparison the data from the temperature stations which the UC Cooperative Extension has been operating throughout the vineyard regions in San Luis Obispo and Santa Barbara County for the past several years.

The question which was most commonly asked throughout the 2010 season was “how many days behind are we?” Based on detailed regional growing degree day measurements, the season became more delayed as it progressed, and by the end of October some areas were over five weeks behind their 2008-2009 degree day accumulations, with the inland areas being most notably affected.

For the complete article in pdf format, please see: Just how cool was the 2010 growing season?