The start of wine grape growing season in California’s Napa Valley now comes nearly a month earlier than it used to because of the region’s warming climate, according to a new study from a team led by UC San Diego Scripps Institution of Oceanography researcher Dan Cayan.

The research, published online in the International Journal of Climatology on June 29, is based on an analysis of local temperature records spanning 1958-2016 that charts the effects of natural climate variations such as the Pacific Decadal Oscillation and the growing influence of human-caused climate change upon the seasonal rhythms and shorter term temperature extremes in Napa Valley.