The harvest began on Monday.
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David Sarabian is worried because a storm could cause mold and mildew issues.
"Just before the rain, the night before or the morning before, we're going to cover them up and roll them just to protect them from the rain so if the rain hits them, it won't be direct," he said.
Many local growers say they're at least a week away from laying their grapes on trays.
But this variety, zante currant, comes on earlier than the Thompson variety normally used for raisins. They're smaller and very sweet.
"It's used in the baking and it's used by the baristas where they sell oatmeal," Sarabian said. "It's part of the nut pack that goes into the oatmeal."
The threat of rain is also impacting harvest in other fields.
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Sarabian says crews have been picking as much of the processing tomato crop as they can.
Any tomatoes left that don't get harvested will be treated with fungicide.
The Valley almond crop is also ready to pick in many areas.
Some growers have started to harvest before the skies turn from sunny to cloudy - and possibly bring rain.
Should we get some rain, farmers worry the moisture and humidity could lead to mold problems in some crops.
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