Heavy rain has Southern California on alert for flash flooding and mudslides today, two months after deadly mudslides in Montecito.

Rainfall totals are expected to mostly range from 2 to 5 inches across coastal and valley areas and 4 to 8 inches across foothills and coastal slopes. But the top rain total has been in San Luis Obispo County, which has seen 9.5 inches

As of 11 a.m. local time, Santa Barbara had seen 2.7 inches of rain and Montecito 2.5 inches.

Rainfall rates could be as high as an inch an hour, potentially causing mudslides and rockslides.

Santa Barbara County Sheriff's patrol the Glen Oaks Drive area near East Valley Road and San Ysidro Creek Wednesday as s mandatory evacuation remains in place, March 21, Montecito, Calif. (Al Seib / Los Angeles Times/Polaris) Santa Barbara County Sheriff's patrol the Glen Oaks Drive area near East Valley Road and San Ysidro Creek Wednesday as s mandatory evacuation remains in place, March 21, Montecito, Calif.
Muddy water runs downstream as heavy rain falls along a stretch of Highway 33 near Ojai, March. 21, 2018.(Luis Sinco/Los Angeles Times/Polaris) Muddy water runs downstream as heavy rain falls along a stretch of Highway 33 near Ojai, March. 21, 2018.

In Santa Barbara County, 30,000 people were told to evacuate, including residents of Montecito.

This photo from video provided by the Santa Barbara County Fire Department shows Montecito Creek flowing alongside debris left over from January mudslides in Montecito, Calif., March 21, 2017.(Mike Eliason/Santa Barbara County Fire Department via AP) This photo from video provided by the Santa Barbara County Fire Department shows Montecito Creek flowing alongside debris left over from January mudslides in Montecito, Calif., March 21, 2017.

The Jan. 9 storm in Montecito killed 21 people, left two children missing and destroyed many homes.

Dave Zaniboni of the Santa Barbara County Fire Department described the aftermath of the January mudslide as a "battlefield" and "unrecognizable."

"I've been doing this for 32 years and I've never seen anything just so tragic in my life," he told ABC News Wednesday.

Mudflow and damaged homes in Montecito, Calif., Jan. 10, 2018. (Matt Udkow/Santa Barbara County Fire Department via AP) Mudflow and damaged homes in Montecito, Calif., Jan. 10, 2018.
Police drive amid the devastation of a mudslide on East Valley Road in Montecito, Calif., on Jan. 11, 2018.(Juan Carlo/Ventura County Star via USA TODAY NETWORK) Police drive amid the devastation of a mudslide on East Valley Road in Montecito, Calif., on Jan. 11, 2018.
Emergency personnel evacuate local residents and their dogs after a mudslide in Montecito, Calif., Jan. 9, 2018.(Kenneth Song/Santa Barbara News-Press via Reuters) Emergency personnel evacuate local residents and their dogs after a mudslide in Montecito, Calif., Jan. 9, 2018.

The "monster storm" Jan. 9 "dropped a half an inch of rain in 15 minutes and an inch of rain in half an hour,” Zaniboni said, “and that's what caused the debris flow."

Today's storm is expected to be bigger, but over a longer period of time, which eases the debris flow, he said.

Commuters drive under heavy rainfall in Los Angeles, March 21, 2018. A slow-moving storm, billed as an "atmospheric river" began unleashing rain across southern California. Mandatory evacuations have been ordered by officials in Santa Barbara, Ventura and Los Angeles counties.(Frederic J. Brown/AFP/Getty Images) Commuters drive under heavy rainfall in Los Angeles, March 21, 2018. A slow-moving storm, billed as an "atmospheric river" began unleashing rain across southern California. Mandatory evacuations have been ordered by officials in Santa Barbara, Ventura and Los Angeles counties.
Raindrops are seen on a vehicle's window as a woman walks by using an umbrella under heavy rainfall in Los Angeles, March 21, 2018.(Frederic J. Brown/AFP/Getty Images) Raindrops are seen on a vehicle's window as a woman walks by using an umbrella under heavy rainfall in Los Angeles, March 21, 2018.

"Because this storm is so widespread and so long in duration, we're concerned about any heavy cells, any thunderstorm that might center over these mountain areas," Zaniboni said. "Right now, they're doing a great job as far as the creeks and stuff go. They're funneling all the water off the mountains and the creeks are running clear.

"But after Jan. 9 all of those creeks ... were jam-packed, clogged up with debris and trees and boulders and houses," he added. "Since Jan. 9, the Army Corps of Engineers has been in here working hand-in-hand with Santa Barbara County Flood Control; they've been working around the clock and got all of those debris basins and all those creeks clear."

The rain will continue all day and get lighter by later this afternoon and evening.

ABC News' Kayna Whitworth and Scott Shulman contributed to this report.