The U.S. state of California faces a tough weekend ahead for citrus growers, as temperatures in the San Joaquin Valley threaten to fall to some of the lowest levels in years, agricultural weather forecaster John Hibler said.

"We’re looking at low to mid-20s coming up on Saturday morning, Sunday and possibly Monday morning as well. So this is a multi-day event that we’re dealing with out here," Hibler said.

"Any time you get below 28 degrees (-2°C) for as much as 10 hours sometimes, which we’re anticipating, the fruit has a pretty tough time dealing with that."

Mid-December to mid-January is the valley's worst month for weather. Hibler explained, however, that temperatures this low only happen ever seven to 10 years.

"We’re fortunate in one respect, that the citrus fruit is later in the season out here. It has a higher sugar content, so it can hold up better than it can say back at Christmas time," he said.

Willits & Newcomb, Inc general manager Gary Moles said their citrus tree nursery anticipated losses in what threatened to be the worst frost in years.

"We’re backed up against the mountains. Sometimes the cloud cover doesn’t leave as soon as they project but as soon as it does leave, it’s supposed to be cold," Moles said.

He explained that it is still too early to forecast the extent of damage.

"You don’t know quite how much until springtime happens. Sometimes it’s just burn. Sometimes the trees split and the fruit gets damaged. Sometimes you can’t tell that, unless it’s severe, until the weather changes," Moles said.

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