Officials hope to decide later on Wednesday whether to issue a mandatory evacuation order before the storm reaches the southern half of the state late Thursday or early Friday.
"Today is the day to prepare and have everything ready to go," said Suzanne Grimmesey, a spokeswoman for the Santa Barbara County Emergency Operations Center. "For people that have functional needs or large animals, we recommend that now is probably a good time and not to wait."
She did not know how many people may have left the area.
Montecito and neighboring communities on the coastal foothills of the Santa Ynez Mountains lie below slopes burned bare by the largest wildfire in recorded California history as well as other fires in recent years.
Evacuation fatigue for some residents is a factor. Some evacuated multiple times during the wildfires, and then again when the mudslides hit.
Geologists estimate that the scorched earth won't grow vegetation for three to five years, meaning every time a major storm moves into the area, residents may be asked or ordered to evacuate.
"It's kind of our way of life until the land grows back," Grimmesey said.
The latest storm was expected to begin in the far northern portion of the state Wednesday afternoon then ramp up on Thursday, when a blizzard warning goes into effect in much of the Sierra Nevada.
The National Weather Service said northern mountains were expected to receive 3 feet (0.9 meter) to 5 feet (1.5 meters) of snow, and up to 7 feet (2.1 meters) in localized areas.
The dump would be a boon to the Sierra snowpack, which is vital to the state's water supply but is only about a quarter its normal size at this time of year for the winter season.
Forecasters, however, focused on a host of hazards for anyone trying to drive through the mountains.