Citrus growers across the Central Valley are getting ready for sleepless nights the rest of the week.
With forecasts showing temperatures in the mid-20's to low 30 degrees, there's the potential for a lot of harm to the industry.
"This is the time of year we expect it. But this could turn out to be a major, hard freeze," says Bob Blakely with California Citrus Mutual.
Blakely says the citrus crop in Fresno, Tulare and Kern Counties is worth a whopping $1.5 billion dollarsand 85% of this year's crop is still on trees.
Navel oranges are being harvested right now; the harvest began the third week of October.
The harvest of the Satsuma variety is winding down, and Clementines are being harvested right now.
"Mandarines are the most susceptible. You will start to see the wind machines on when it hits 33 degrees," says Blakely.
Navel oranges growers won't turn on their fans until temperatures reach 29 to 30 degrees.
For now, Blakely says growers are all following the same advice: "Make sure your pumps are working, and that the water is lined up. Have your propane tanks full, too."
The National Weather Service warned California Citrus Mutual that temperatures could drop to the low to mid 20's early Monday morning.
"There's the potential for some damage if it lasts," says Blakely.
Should there be any damage, it could take three to four weeks to show up.
Nearly 270,000 acres of citrus grow in California. 110,000 acres grow in Tulare County.