California’s Central Valley faced one of its few frost nights of the season Jan. 1, but emerged from it with no significant damage to mandarins or navel oranges.

Cold temperatures hit citrus production areas from Bakersfield to Madera. The thermometer reached 27 degrees in Lindcove and 32 in Terra Bella.

“It was probably the coldest night this season, but compared to last year there have not been serious frost nights,” said Alyssa Houtby, director of public affairs at Exeter-based California Citrus Mutual.

As of Jan. 2, navel growers reported three to five critical nights, compared to 24 or so in the same period last year. Mandarins have had about 14 critical nights, down from 30 to this point last year.

“The mandarins have been feeling a little bit more pressure,” she said. “They had to run wind machines (Jan. 1) for eight to 10 hours. Some orange growers didn’t have to run wind machines at all; some ran them up to five hours.”

“The fog has been protecting the oranges a lot this year,” Houtby said. “When they’ve predicted cold, the fog has come in and created some nice protection.”

Minimal damage was reported to mandarins on the edges of protected areas. The wind machines and an inversion layer boost grove temperature by three to five degrees. Rainstorms that have pelted California for the last month or so also helped, as water warms the ground.

The industry spent about $100 million on frost protection in the 2011-12 season.

It costs about $30 per hour to run a wind machine. There are about 16,300 of the machines in the valley covering more than 180,000 acres of citrus crops.

About 85% of the $2 billion crop there is still on the tree.

This season’s crop gained sugar content ahead of last year’s, making it less vulnerable to cold.