Do freezing temperatures harm the vines? Do those big fans in the vineyards keep the workers cool?
Frosts are welcome and frequent, sometimes occurring 20 to 30 times or more during the winter months. They actually harden fruiting buds and force vines into dormancy providing a healthful rest before the next growing season.
Frost becomes a predator as soon as buds pop out those tender leaves and shoots around the middle of March through April. When skies clear and the night air grows still; temperatures plummet and winery alarms sound the warning. The battle begins.
Where water is scarce (the vineyard is dry farmed or drip irrigated), those big ubiquitous propellers push warmer supernatant air into the low spots displacing the heavier, frosty air.
Where water is abundant, overhead sprinklers apply water at a rate of 50 gallons per acre per minute which freezes and encases the shoots in a protective layer of ice. However, if a well goes dry during a series of freezing nights, the war is over unless there is a reservoir to tap which allows the well to recover.