Cold Canadian air will move into the San Francisco Bay Area this weekend followed by colder air next week that may bring temperatures into the 20s in some places, National Weather Service officials said.
Low temperatures in the morning Sunday, New Year's Day, will be in the 30s, though areas closer to the water will be warmer.
Starting Monday though, lows will be in the low 30s in most areas and by mid-week some residents may see temperatures in the low 20s.
Current weather models for much of next week show a slight chance of rain with a slight chance of snow in higher elevations, weather officials said.
Meanwhile, people at the Trinity Center for the homeless in Walnut Creek said they have received many calls from others seeking shelter.
Donna Columbo, who runs the Trinity Center, said there are about 150 people in the area who live outside.
With below-freezing temperatures expected, Columbo fears for their health.
"If it's 40-degress below or raining, you run the risk of hypothermia," Columbo said.
People need to register at the Trinity Center and be screened before they are eligible for the overnight shelter.
For those with roofs over their heads, there is another set of worries. Former plumber Howard Gibbs said now is the time to insulate exposed pipes.
As for plants, nursery specialist and florist Shawna Anderson said to water them now.
Anderson also suggests spraying them with plant protector.