COUNTYWIDE : War on Jack Frost Matter of Degrees

Deep in the basement of what was once the county’s fumigants storehouse in Santa Paula, big wooden crates are filled with nearly 2,000 agricultural thermometers. Although they cost only about $30 each, the devices are invaluable in helping the county’s citrus and avocado growers forestall damage from the coming winter’s frosty nights.

Four men work as a team among the sturdy thermometers, pulling them carefully out of the crates, placing them gently into water kept at slightly above 32 degrees and checking the reading’s accuracy.

The men--three of them meteorologists with the National Weather Service and one the foreman of a local citrus packinghouse--are checking the thermometers this week in cooperation with the county agricultural commissioner’s office for the growers, who use the thermometers to determine if steps should be taken on cold nights to protect crops and orchards.

Since citrus fruits and avocados represent $400 million, half of the county’s total agricultural revenue, testing the thermometers is important, said meteorologist Terry Schaeffer. A reading that is inaccurate even by a couple of degrees could mean trouble.

“If the reading is two degrees higher than the actual temperature, the rancher might think he doesn’t have to worry, or if it’s too low he may turn on his wind machines too soon,” he said. Wind machines circulate air among the trees, keeping the fruit from freezing.

“If you can hold off turning on six machines, you can save a lot of power. An accurate thermometer can save ranchers money in frost protection. It’s not like they’d lose their crop, but they might lose money starting crop protection when they didn’t really need to.”

“The ag commissioner’s office has been testing thermometers since the 1920s,” he said. “We’ve probably checked 250,000. . . .”