The central San Joaquin Valley’s freeze warning passed Monday after a weekend of freezing temperatures that had citrus growers running wind machines and taking other measures that cost more than $25 million.
The National Weather Service doesn’t expect to issue another freeze warning Monday night, but temperatures will still be in the upper 20s to low 30s for the Valley, said meteorologist Modesto Vasquez with the weather service office in Hanford. Patchy fog and frost also are forecast for the Valley.
Although temperatures didn’t get as low as predicted – some rural areas were expected to stay at 25 degrees for as long as six hours – it got very close in some places. Fresno hit a low of 32 Monday morning, Vasquez said, with Lemoore coming in at 28 for the coldest spot reported.
Alyssa Houtby, director of public affairs at California Citrus Mutual, said growers throughout the San Joaquin Valley ran their wind machines over the weekend, but it actually was great weather for oranges.
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“A little bit of cold weather is beneficial for fruit,” she said, explaining that it helps store the citrus on the trees for longer, while warm weather accelerates ripening. She said most growers reported running their machines for about 16 hours this past weekend, covering about 44,000 acres in Central California.
No citrus crop damage was reported, but protection came with a price. “California Citrus Mutual estimates Central Valley citrus growers spent a total of $25.1 million in frost protection this weekend alone to protect the region’s $2.5 billion crop,” Houtby said.
Mandarin and other easy-peel citrus growers generally turn on their machines when temperatures get below 33 degrees, Houtby said, but navel oranges are pretty hardy and can withstand a bit colder temperatures. The wind machines can raise temperatures up to 5 degrees, and they work by lifting warm air from the ground and circulating it through the trees.
Some growers have started covering their trees with special covers that let the light in but keep the cold air out. The white covers are only used for “baby trees” with no fruit, said Houtby, and usually are put on beginning in December to protect the growing trees.
A warmup is in order, the weather service said, with the Fresno area reaching daytime highs in the upper 50s and low 60s during the rest of the week.
There is a slight chance of rain on Friday night into Christmas Eve morning, with Yosemite likely seeing showers Friday night and a possibility of a snow shower Christmas Eve morning. Christmas Day should see mostly clear skies.