We spoke with Michael Larner out at his Ballard Canyon Vineyard in June and asked about how heat spikes affect him around Harvest.
“The nature of Syrah is that it is always harvested in October.” “We never see heat spikes in October so we don’t have to panic.”
Heat spikes cause sugars to go up. As the vines become stressed for water the first place they get it from is the berries. As the berries dehydrate from the vine pulling moisture the sugar levels increase and concentrate. This is only temporary and the sugar levels will stabilize again when the temperature drops or when the vine gets more water.
Watching the weather and planning ahead they can water before a heatspike so that the sugar levels don’t soar. This gives the clients a couple more weeks before harvesting when the wineries are typically full at the end of harvest. Michael says he tells clients “Let me water it, rather that you having to water it in the winery!”.