In part of the continuing saga of the bitterly cold air invading the interior West and Plains this week, Arctic air will also reach into California, setting the stage for a frost and freeze and a risk to agriculture.
Temperatures will dip to record low levels on one or more dates over the San Joaquin Valley and the Central Coast, home to a wide variety of agriculture, including vegetables and citrus, ranging from avocados and strawberries to lettuce and oranges.
According to AccuWeather.com Western Weather Expert Ken Clark, "It is not so much that it has never gotten this cold in the region before, but rather it rarely gets this cold this early in the winter season."
Agricultural interests will need to take preventative measures to raise temperatures in the fields and groves such as spraying water and running wind machines.
In some cases, temperatures will challenge records in the books for more than 100 years with lows forecast to be in the upper 20s. For example, the record low at Fresno, Calif., is 28 degrees each date from Dec. 4 to 6, set during the years 1897, 1903 and 1891, respectively.
Record lows around Fresno dip into the upper teens and lower 20s later in the month.
Temperatures are forecast to plunge into the upper teens and lower 20s around Paso Robles, the middle 20s around Porterville and near 30 degrees around San Luis Obispo, Calif., where record-challenging chill and a freeze are forecast.
"Temperatures are likely to drop below freezing for multiple hours, which is more of a concern for agriculture than an hour or two near or just below freezing," Clark said.
The rind on California citrus crops is thicker and offers more protection from freezing temperatures, when compared to those in Florida.
According to Alyssa Houtby, director of public affairs with California Citrus Mutual (CCM), "The critical temperature for our navel oranges and lemons is 28 degrees, but for mandarins it is 32 degrees."
Houtby stated that only about 15 percent of this year's citrus crop has been harvested as of Dec. 3.
CCM also said that some fruit damage is expected for areas that dipped into the low 20s Wednesday night, but it will take three to four weeks for the full the extent of the damage to be known.
"It is anticipated that the mandarin crop will sustain the most damage, particularly in the coldest areas along border rows where wind machines and water protection are less effective," Houtby stated.
A severe, long-duration freeze in December 1990 did more than damage the crop, as it took its toll on trees.
According to AccuWeather.com Agricultural Meteorologist Dale Mohler, "The freeze this week in California is not likely to approach the damage of 1990 nor cause significant damage to citrus trees."
Other California cities that have a chance at setting new daily low temperature records during this Arctic outbreak include Bakersfield, Redding, Sacramento and San Francisco.
The weather pattern is forecast to deliver temperatures averaging 10 to 15 degrees below average over a several-day period.
Meanwhile, over much of the Los Angeles Basin and around San Diego, high temperatures are projected to be in the 50s for the second half of the week, despite sunshine.
It might feel more like late October rather than late May in the Northeast early Saturday morning as temperatures dip well below normal.
More clouds and cooler weather can be expected across the Bay Area through the holiday weekend and into the new week.
Another round of heavy rain and thunderstorms will move into the Plains over Memorial Day weekend, bringing the threat of flooding.
Cloudy skies and cooler weather will linger across the Los Angeles area through the holiday weekend and early in the new week.
Memorial Day marks the unofficial start to summer and summer warmth will dominate the Northeast next week, but that does not mean an end to shots of cooler air.
Showers and thunderstorms threaten to interfere with Memorial Day festivities across roughly two-thirds of the United States.
New Hampshire (1814)
Merrimac, Litchfield, Londonderry and North Chester, NH; Tornado and hailstones with 11-inch circumference weighing 1/2 pound.
Late May snowstorm blanketed eastern part of state with 4 to 6 inches.
Washington, DC (1925)