"We're going to have some really chilly nights ahead of us," Bonnie Bartling, a National Weather Service specialist, said about Southern California.
Bartling predicted Saturday that overnight low temperatures in the San Bernardino Mountains this morning would be between 1 and 9 degrees above 6,000 feet, and 10 to 20 degrees for those below 6,000 feet.
In the early morning hours, the Big Bear Lake area, which ranges from 6,750 feet to 9,000 feet, was expected to have a low temperature of minus 3 degrees, with wind chill values as low as minus 15. Tonight's low temperature was forecast to be slightly warmer - zero degrees.
And the need to bundle up will continue this week as the region sees some of the coldest January weather since 2007, dropping to sub-freezing temperatures in many areas and sub-zero temperatures in some, according to the National Weather Service.
The coldest weather was expected to arrive in the early morning hours today, prompting officials to issue a freeze warning for much of the Southland, Bartling said.
The NWS issues a freeze warning when temperatures are expected to fall below 28 degrees for at least two consecutive hours.
"We're having a really cold winter this year. A lot of locals are talking about it," said Don Sidener, a U.S. Forest Service forestry technician stationed at the Big Bear Discovery Center.
Having been at Big Bear Lake for 22 years, Sidener said the coldest temperature he recalled was 14 degrees below zero.
"The lake is frozen over in many sections," he said, "but there are still sections of open water."
The lake has been closed to larger boats since October, Sidener said. Small craft such as canoes are still allowed on the icy lake, though not recommended.
Those heading up to Big Bear Lake were required to have chains for their vehicles, though they were not required Saturday, Sidener said.
At the Mountain High ski resort in Wrightwood, the cold weather did not keep skiers and snowboarders away from the slopes, which received 3 to 5 inches of "fresh powder" on Thursday, resulting in excellent ski conditions, said Kathy Cornell of Mountain High guest services.
Skiers and snowboarders filled parking lots bright and early Saturday, despite temperatures barely out of single digits, she said.
Some portions of the Los Angeles County mountains and Antelope Valley were predicted to experience single-digit temperatures early today, according to an NWS statement.
A low-temperature of 18 degrees was predicted this morning at Mount Wilson in the Angeles National Forest, Bartling added.
Low temperatures at Big Bear Lake are expected to be in the 20s Tuesday through Friday, with high temperatures rising to 53 degrees by the week's end.
But the cold weather is not expected to be accompanied by precipitation. No rain predicted over the next 10 days.
In addition to the cold weather, the Southland is also expected to have strong Santa Ana winds beginning tonight, Bartling said.
The NWS issued a wind watch for much of the area for tonight through Monday, as gusts in excess of 60 mph were predicted to blow through mountains and some valleys.