Unusual Weather Leads to Dismal Harvest in California

Amid a harvest impacted by late winter temperature fluctuations, California is expecting a 30-percent drop in olive oil production this season.

Oct. 2, 2018
By Daniel Dawson

Recent News

In California, many olive farm­ers are scratch­ing their heads after a series of unusual weather events has left this year’s olive har­vest 25 per­cent lower than last year.

We are spec­u­lat­ing a very warm period in February woke the trees up and a freeze in March shut them down.- Jeff Martin, Frantoio Grove

“I have zero olives and will not har­vest any­thing,” Jeff Martin, an olive farmer and award-win­ning pro­ducer based in Santa Clara County, told Olive Oil Times.

At his farm, roughly 35 miles south of San Jose, an unsea­son­ably warm period at the end of winter caused the olive trees to bloom. These blooms were then dam­aged by an early spring frost, which ren­dered the trees barren for the rest of the har­vest season.

“We are spec­u­lat­ing a very warm period in February 2018 woke the trees up and a freeze in March shut them down,” he said. “In farm­ing, you just have to live through the down years.”

Martin’s case is not an iso­lated inci­dent. Many coun­ties across California, but espe­cially in the north and center of the state, were affected by these tem­per­a­ture fluc­tu­a­tions. Even some grow­ers as far south as Ventura County reported frost damage.


“We won’t har­vest for a couple of months still, but it is easy to tell that [our yield] will be much less, prob­a­bly a 50 per­cent reduc­tion,” Phil Asquith, the owner of Ojai Olive Oil, told Olive Oil Times. On top of the tem­per­a­ture fluc­tu­a­tions, Asquith said the hot summer took its toll on his trees as well.

“Swings in tem­per­a­ture from cold to hot, a ‘false spring’ fol­lowed by more heat, also sear­ing heat waves up to 120 degrees [all dam­aged our crop].” he said.

However, not all pro­duc­ers were impacted equally by the weather. Several from dif­fer­ent parts of California told Olive Oil Times that they were not affected at all by the late winter and early spring tem­per­a­ture fluc­tu­a­tions.


“We did not expe­ri­ence what others expe­ri­enced as we are a bit warmer than other areas,” Karen Bond, the co-owner of Bondolio in Yolo County, told Olive Oil Times. She expects to see a slight decrease in her pro­duc­tion this year, but attrib­uted it to being an off year.

According to the California Olive Oil Council (COOC), which rep­re­sents 90 per­cent of the state’s olive oil pro­duc­ers, there are more sto­ries sim­i­lar to those of Martin and Asquith than of Bond.


The council’s data indi­cates that California pro­duc­ers will press 2.8 mil­lion gal­lons of extra virgin olive oil this year; a decrease of 1.2 mil­lion from last year.

This is a dis­ap­point­ing figure for Patricia Darragh, the exec­u­tive direc­tor of the COOC, but still not as bad as it could have been. Back in June, an unof­fi­cial esti­mate from the coun­cil fore­casted that the yield may have decreased by as much as 35 per­cent.

In fact, Darragh is opti­mistic that this is only a bump in the road for California pro­duc­ers and said that prices will not be affected. She is not alone in her opti­mism. Every single pro­ducer inter­viewed by this reporter, even those unaf­fected by the tem­per­a­ture fluc­tu­a­tions, said he or she expected to have a better har­vest next year.

However, there is no ques­tion in Darragh’s mind that the weather is respon­si­ble for this year’s sub­stan­tial decrease.

“My under­stand­ing is that it is almost all weather-related,” Darragh told Olive Oil Times. “Even though olive trees are alter­nate-year bear­ing, that has not been sig­nif­i­cant to date in California.”

The big ques­tion loom­ing for her and all of the state’s pro­duc­ers then becomes: will California become increas­ingly sus­cep­ti­ble to late winter thaws fol­lowed by early spring freezes?

Two plant sci­en­tists and an agri­cul­tural engi­neer told Olive Oil Times back in June that they thought California is becom­ing more sus­cep­ti­ble to these tem­per­a­ture fluc­tu­a­tions. There is cur­rently no data avail­able to con­firm whether or not this is the case.


“However, there has been some anec­do­tal evi­dence of [these] events,” Kripa Jagannathan, a member of the Energy and Resources Group at UC Berkeley, told Olive Oil Times. “So we are trying to dig into the data to see what we can find.”

Jagannathan is part of a team that is study­ing how the freeze risk for sub-trop­i­cal and decid­u­ous trees in California will be impacted by cli­mate change.

She said the team is still in the very ini­tial stage of their research, but does have one work­ing hypoth­e­sis: the last frost date is chang­ing more slowly than the rate at which the spring is warm­ing. This would lead to trees bloom­ing ear­lier in the season and cause them to be more sus­cep­ti­ble to harm from that lin­ger­ing last frost date.

“If the last frost date advances at a rate slower than the phe­no­log­i­cal shift in bloom times, then trees are likely to expe­ri­ence an increased frost risk,” she said.

Paul Ullrich is the head of the UC Davis Climate and Global Change Group. He told Olive Oil Times that abrupt tem­per­a­ture fluc­tu­a­tions, such as the ones expe­ri­enced ear­lier this year in California, are caused by cold air escap­ing from the polar jet stream and blow­ing into lower lat­i­tudes.

“On the purely mete­o­ro­log­i­cal sidemid-lat­i­tud­es­these abrupt tem­per­a­ture fluc­tu­a­tions are nom­i­nally caused by arctic air intru­sion, where cold arctic air is able to escape into the mid­lat­i­tudes because of a weak polar jet stream,” he said.

According to data kept by the National Oceanic and Atmospheric Administration, polar intru­sions through­out the middle of March low­ered California’s daily aver­age tem­per­a­tures sub­stan­tially com­pared with pre­vi­ous years. This phe­nom­e­non is likely to have lead to the frost events that dam­aged so much of California’s olive crop.

While there is no solid evi­dence link­ing cli­mate change to a weak­en­ing polar jet stream, Ullrich said this link should be inves­ti­gated fur­ther.

“Although it hasn’t been proven defin­i­tively, it is the­o­rized that under cli­mate change we will see a weaker polar jet because of loss of arctic sea ice, which would then lead to a higher prob­a­bil­ity of a cold air intru­sion event,” he said.

In other words, California pro­duc­ers may have to brace for more February thaws fol­lowed by March freezes.