The National Weather Service has issued a frost advisory from 3 a.m. to 9 a.m. Wednesday.
Temperatures will likely drop down to the 30s from Modesto to Marysville.
Farmer Mark Foley in Newcastle is trying to stay ahead of the frost.
"I am monitoring the soil ... you can see the way it clumps together..." he said.
Foley, who has 1,000 mandarin trees, is happy it won't be a hard freeze. But to play it safe, he may water his soil before nightfall to keep his crops warm.
Meanwhile, Tuesday was a great day to be in the firewood business.
"It's overwhelming. You've got so many people wanting [firewood] like it's an emergency,"said Linda Noe with Tony's Firewood in Citrus Heights.
She said she is used to the phone ringing off the hook for delivery requests in January, but not November.
Her delivery drivers are booked up for the next eight days.
"We can't keep up with the orders! Well, we can, but it's going out as fast as we are bringing it in," Noe told FOX40.
The National Weather Service warns that sensitive outdoor plants may be damaged or killed. A cover from your local hardware store can save them.