Many growers are using water and wind machines to keep the frost away. Others are burning peach pits to protect their crops.
The citrus industry is worth about $2 billion a year and much of it is grown right here in the central valley. Damage from a major freeze would have a huge economic impact.
"When you talk this time of year – December, January, February – it’s citrus for so many folks that pays the bills. Critical jobs to so many people up and down the valley there," Ryan Jacobsen, from Fresno County Farm Bureau said.
Farmers with crops at risk typically stay up all night monitoring the weather. Prolonged temperatures below 28 degrees could do some harm.