SAN DIEGO (AP) — Oddly enough, even polar bears at the San Diego Zoo are getting a helping hand with the unseasonable freezing temperatures sweeping across California.

Zookeepers turned up the heat for some animals and offered shelter to polar bears as a cold snap continues through the weekend, promising to bring the coldest overnight temperatures.

While polar bears tolerate frigid climes, the zoo animals lack the fat layers that naturally occur in the wild to fully protect them from the cold so zookeepers offer them shelter and "warming apparatuses" in case they seek it, zoo spokeswoman Jenny Mehlow said.

"The animals do take this in stride because they're wearing a nice, warm fur coat," she said.

The National Weather Service forecasted near-record low temperatures Saturday and Sunday nights.

Frost and freeze warnings were in effect early Sunday for parts of San Diego County with lows in some areas dipping to 25 and even lower in the mountains, according to the weather service. On Saturday, the town of Ramona in eastern San Diego County recorded a low of 23 degrees, breaking the 24 degrees set in 2007.

Temperatures dropped to 5 degrees in the snow-covered Big Bear mountain resort east of Los Angeles on Saturday. Even the snowbird haven of Palm Springs saw temperatures hover around freezing at night.

Freeze warnings were issued for Sunday morning across wide swaths of the Los Angeles Basin. Residents were being urged to cover outdoor plants and bring pets inside.

In Sonoma County, homeless shelters handed out extra warm clothes to protect people from frigid overnight temperatures.

In the San Joaquin Valley, the heart of California's citrus production, growers prepared for another round of freezing temperatures early Sunday after seeing little crop damage since Thursday night.

"Last night was not a problem, but tonight and Monday morning could have the potential to be pretty cold," Paul Story, director of grower service at California Citrus Mutual, said Saturday.

Farmers run wind machines and water to protect their fruit, which can raise the temperature in a grove by up to 4 degrees, Story said. Existing moisture, sporadic rain and cloud cover can also help keep in heat.