As Southern California braces for Hurricane Hilary, volunteer organizers are driving the streets of Los Angeles this weekend passing out tarps and plastic bags to people without homes so they can try and keep themselves and their belongings dry.

The National Hurricane Center issued a tropical storm warning Friday and city officials warned residents to prepare for damage that's expected when Hilary reaches Southern California Sunday. On Saturday, state officials warned they are expecting a "very, very dangerous and significant" storm.

For people without shelter, that danger is exponentially greater. An estimated 75,000 Los Angeles County residents don't have homes or access to permanent shelter. “There are people that are going to die," said Andreina Kniss, an advocate with homeless outreach group Ktown for All. "Every time these disasters happen there are deaths that could have been prevented,” she said.

People living on the streets are "at risk literally of drowning," said Dr. Margot Kushel, a medical professor and director of the Benioff Homelessness and Housing Initiative at the University of California San Francisco. They could be swept away by floodwaters or die of hypothermia if they get wet and can't dry off. They are also more at risk for serious injuries from falling trees or debris.

"You and I aren't going to get hit by a car while we're sleeping in our bed, but if every time you need to go the bathroom, you have to cross the street, you're much more at risk," Kushel said.

In the past year, less severe storms have already had deadly effects in California. In January, two people in Sacramento were killed after powerful winds caused trees to fall on top of their tents. Last year, three homeless people were found dead amid storm wash east of Los Angeles in Ontario, California, following a Nov. 8 storm.

'It will be rough'

Carla Orendorff, an organizer with Aetna Street Solidarity in Los Angeles' Van Nuys neighborhood said she is most worried about elderly people and those with disabilities. This week, she's helped create platforms so people can raise themselves off the ground to avoid standing water.

“People are doing their very best to survive, but it will be rough,” Orendorff said.

City parks and recreation facilities were "pre-identified" to potentially be used as shelters for people who need to evacuate from certain areas, Los Angeles Mayor Karen Bass said at a Friday night press conference, when she also cautioned people to stay off the streets.

Federal housing officials also warned people to get inside if they can. "We are encouraging everyone to have a plan that puts safety first, especially for our currently unhoused or homeless neighbors, by seeking community resources and emergency shelter in advance of the storm’s arrival," said Andra Higgs, spokesperson for U.S. Department of Housing and Urban Development.

More homeless swept from neighborhoods living in low-lying areas

Across Los Angeles County, more people without shelter are living in low-lying areas after being pushed out of neighborhoods when sanitation workers began doing more frequent homeless sweeps in January, advocates told USA TODAY. The sweeps, described by Soleil Ngo of West Adams Mutual Aid as "very whack-a-mole," have prompted people to live in hard-to-access places in order to avoid being swept out again.

Increasingly, people are living in “hidden spaces” or “hidden up under” topography in order to be “someplace that's out of the way," Ngo said.

Orendorff said more people are living in their tents along river beds, under bridges, in tunnels and underground — areas extremely vulnerable to flooding. “We are especially concerned that we will not be able to reach people to warn them and help our communities prepare,” Orendorff said.

Mercedes Márquez, chief of housing and homelessness in the mayor's office, said city officials began outreach Friday to low-lying areas to try and warn people of the impending storm.

Volunteers try to help unhoused people stay dry

On Friday, Kniss and her husband passed out tamales and dozens of tarps they bought at Home Depot to people in Los Angeles' Koreatown neighborhood. They also helped people secure their tents in preparation for high winds and passed out new tents to people who needed replacements.

She said many had not been contacted by outreach workers as of Thursday and did not know a hurricane was coming.

"There's really no targeted program specifically for unhoused people, which there should be," Kniss said. "They're the most at risk of dying."

In Palm Springs, California, authorities are flying around in helicopters and using drones with speakers warning homeless communities to evacuate to higher ground.

'Imagine you had no walls and no roof'

People without shelter in California say storms regularly cause them to lose important belongings, making it harder for them to secure jobs and apartments, according to a report released in June by Kushel's Benioff Homeless and Housing Initiative.

A large percentage may lose official documents to rain water in the coming days as Hilary soaks the southwestern U.S., Kushel said. They could also lose government-issued cellphones that provide a critical communication lifeline.

"Suddenly imagine that you had no walls and no roof and everything got soaked," she said. "You are cold, you're shivering, the temperatures drop at night and there's no escape from it."

Contributing: Erin Rode, Palm Springs Desert Sun