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Davis Today
By the People, for the People
Tule Fog Aids Central Valley Fruit and Nut Crops
Prolonged periods of dense fog help offset late arrival of cold temperatures, providing adequate chilling for trees
Published on Feb. 11, 2026
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Prolonged periods of tule fog during the winter helped offset the late arrival of cold temperatures in California's Central Valley, likely resulting in adequate chilling for fruit and nut trees. The persistent fog helped depress temperatures and reduce the number of warm hours that can negatively impact dormancy, according to experts. While chill hours may not be at record levels, growers say the trees should have enough chilling to set a strong bloom and crop.
Why it matters
Adequate chilling is critical for fruit and nut trees in the Central Valley to properly enter dormancy and set a healthy crop the following season. The region has seen inconsistent winter weather patterns in recent years, making it challenging to predict how trees will perform. The prolonged fog this winter appears to have helped compensate for the late arrival of cold temperatures.
The details
NASA described a tule fog blanket stretching 400 miles from Redding to Bakersfield from November 24-December 9, 2025, as 'unrelenting.' The dense fog returned in January for several more days. Experts say the fog likely decreased the number of warmer hours that can negatively impact tree dormancy. While chill hours may not be at record levels, growers say the trees should have enough chilling to set a strong bloom and crop.
- The tule fog stretched from November 24 to December 9, 2025.
- The dense fog returned in January 2026 for several more days.
The players
Ted De Jong
A University of California, Davis, pomology professor emeritus.
Mel Machado
The chief agricultural officer at Blue Diamond Growers.
Franz Niederholzer
A UC orchard systems adviser for Yuba, Sutter and Colusa counties.
Bob Beede
A UC Cooperative Extension farm adviser emeritus in Kings County.
Jim Ferrari
A grower of cherries and walnuts near Linden.
What they’re saying
“I do believe that the chill may have been more effective this year because of so many days with fog.”
— Ted De Jong, University of California, Davis, pomology professor emeritus (AgAlert)
“Are we fat with chill hours? No, but we're OK for almonds.”
— Mel Machado, Chief agricultural officer, Blue Diamond Growers (AgAlert)
“The delay in significant chill accumulation that occurred this winter has been compensated for by having these extended periods of cold, foggy weather, which increased the amount of chilling that accumulated each day.”
— Bob Beede, UC Cooperative Extension farm adviser emeritus, Kings County (AgAlert)
The takeaway
The persistent tule fog in California's Central Valley this winter helped offset the late arrival of cold temperatures, likely providing enough chilling for fruit and nut trees to set a healthy bloom and crop despite inconsistent weather patterns in recent years. Growers are optimistic that the fog-induced chilling will help ensure a strong season ahead.
