It happened in Felton on East Zayante Road around 1:20 p.m. on Friday.
The California Highway Patrol for Santa Cruz County said rainfall can loosen soil, though they haven't confirmed that was the case.
RELATED: Preparations underway for storm Sunday and Monday
"I can't say for sure that it is due to the rain, to the weather. But the area that we are in currently, near the fatal collision site, it's moist still," CHP Santa Cruz Public Information Officer Alyssa Gutierrez told ABC7 News.
However, there is much more than moisture in the forecast, adding to the concern of what's to come.
Fierce winds, heavy rainfall, downed trees and dangerous debris flow are expected this weekend. These are reasons why mountain residents are preparing now.
"Stocking up on canned goods and water, and that's probably about it," Boulder Creek resident, Jim Hughes explained. "It's the folks that are living close to the burn scars, where the fire was, I think, that have the most risk right now."
VIDEO: Clogged storm drains cause North Bay flooding, public works crews standing by for busy weekend
Naomi Murphy and her sister live in Bonny Doon, just above the CZU Complex Fire burn scar. Murphy said their drive home cuts straight through the danger zone. So their pre-storm plans included getting groceries, fueling up, and then hunkering down.
"It just kinda goes hand-in-hand with living up here," Murphy shared. "It's just the chance you take, you know, with living up here in the mountains."
She said residents are getting ready to face one disaster after another.
"My neighbors are out getting their ditches ready so that our water can kind of flow down," Murphy described. "So we don't get flooded out from this big storm coming in."
RELATED: Bay Area rain storms to grow in strength, soak region into next week
Gutierrez with CHP Santa Cruz said the big danger is the downed trees and debris flow.
The county defining defined "debris flow" in their Evacuation Warning issued Friday night as, "Fast-moving masses of mud, rocks, boulders, trees and sometimes homes or vehicles. They move quickly and are often deadly to those in their path."
"We have a lot of mountainsides that have trees that have been here for years. And sometimes just the wind just gets the best of them and knocks them into the roadway," Gutierrez added. "So we never know what we're going to experience, but I believe that the burn scars are probably going to make it a little bit more difficult."
LIVE: Track rain, current weather conditions in Bay Area
Late Friday, Santa Cruz County announced that because of the expected intensity of the incoming storm, it's placing areas in and around the CZU Fire burn scar under an evacuation warning.
The County of Santa Cruz is placing the following zones in an evacuation warning: BOU-E005 BOU-E006-B BOU-E007-B BOU-E008-B BOU-E010 BOU-E011-B BOU-E012-B BOU-E012-C BOU-E020 BOU-E030 BOU-E031-A BOU-E036A BOU-E041-A BOU-E042-A BEN-E002-C BEN-E003-B CRZ-E001-C CRZ-E008-B CRZ-E010-C CRZ-E017-C FEL-E003-B
The County said the Sheriff's Office will begin door-to-door outreach on Saturday, in anticipation of evacuations in higher risk areas.
Zones have been updated for risk of debris flow areas, so residents are encouraged to look up their evacuation zone here.
The County also shared helpful steps for those who are evacuating:
RELATED STORIES & VIDEOS: