Watch out, gardeners.
A one-two punch of cold arctic air that is expected to keep nighttime temperatures at or below freezing for about a week rolled into Davis on Tuesday.
Lows in Davis should fall to 25 degrees on Wednesday and Thursday nights, National Weather Service meteorologist Drew Peterson said — 10 to 15 degrees colder than normal.
The air mass took a northerly route over a high pressure system in Alaska before descending rapidly down the coast. Similar cold snaps happened in 2012 and 2009.
“We see a system like this ever three to five years,” Peterson said.
The arrival of a second front will bring a slight reprieve — with a forecasted low of 37 for Friday night — before the low temperature drops again on Saturday to 28 degrees. It also will bring a slight chance of rain in throughout the weekend.
The cold poses a threat to young citrus trees — especially limes and lemons — and avocados, said Redwood Barn Nursery owner Don Shor. He recommends covering them with a thin translucent “frost blanket, which can be left on day and night throughout the freeze.
Covering plants with sheets or tarps will protect plants from frost in a pinch, Shor said. But unless the fabric is tented over plants using stakes, plants are likely to suffer burns anyplace they touch the material.
Here’s a seasonal fix: If you have large-bulb Christmas lights boxed up in the attic, they can be used to keep a tree warm. Less festive but equally effective: shop lights with 40-watt bulbs. Remember to leave them on all night, Shor said, since temperatures are coldest in the morning.
Shor advises picking fruit on the outside of the tree, just in case. Fruit on the inside of the tree should be OK, he said.
Plants that aren’t native to the area — like bougainvillea, hibiscus and angel’s trumpet — also should be protected. Moving jade plants, aloe vera and other tender succulents close to the house or indoors is also a good idea, Shor said.
Make sure all of your plants — especially those in containers — are well-watered, he said.
Plumber Ray Moran suggests wrapping outdoor PVC or plastic pipe with foam insulation. Doing the same with sprinkler valves, or wrapping them with towels, should protect them from damage. Copper tubing also can be wrapped, but that probably won’t be necessary.
“This should pass fairly soon, so I’d worry more about the plastic tubing,” Moran said.
Elevations as low as 1,500 or even 1,000 feet may see snow this weekend — “it’s too early to say” how much, Peterson said. Those headed to the Sierra could be greeted with six inches to a foot of snow over the weekend.
“If you’re headed up to the mountains, try getting up there early Friday or go Saturday,” he said. “Later on Friday could be a little treacherous. Leaving Thursday would be even better.”
— Reach Cory Golden at [email protected] or 530-747-8046. Follow him on Twitter at @cory_golden