(UPDATED COVERAGE, 1:50 p.m.) Citrus in California’s San Joaquin Valley escaped immediate damage Jan. 10, but growers readied themselves for three more nights of freezing temperatures.

A rainstorm that hit parts of the valley created a potential for ice mark on mandarins or navels. But any losses would take time to show up, according to California Citrus Mutual.

“Friday (Jan. 11) is supposed to be the really cold night,” said Alyssa Houtby, director of public affairs for the Exeter-based trade association. “It will probably get into the lower 20s.”

Temperatures in the valley reached as low as the upper 20s on Jan. 10, but wind machines and watering kept fruit above 32 degrees, making damage unlikely.

Elsewhere in the state temperatures in the low 30s hit production areas of Ventura, Riverside and Imperial counties, according to a news release. No damage was reported there. Nevertheless Riverside, Imperial and Coachella groves were threatened for five early morning hours Jan. 11 due to the greater cold sensitivity of fruit there.

Ventura had pockets as low as 27.

California Citrus Mutual expects some damage to mandarins and navels if temperatures hit the lower 20s, but less overall this winter than last when the industry endured a record number of frost nights.

“It’s been pretty moderate,” Houtby said. “This is the first weekend stretch or few days where it’s going to get into the 20s for any length of time. And it’s later in the season than normal so that helped the fruit get established a little more.”

In the 2011-12 season growers used protection measures — wind machines and watering — an average of 25 to 30 nights. It cost about $100 million, or $300 to $400 per acre. They’re well behind that pace now.

On Jan. 10 growers ran wind machines from six to 10 hours, typically starting from midnight to 2:30 a.m. They were expected to start earlier Jan. 11.

Navel oranges in the San Joaquin Valley are about 25% harvested. The bulk remains on the tree, but could benefit from having had time to set.

Milder temperatures were expected to return Jan. 14.