Flash flooding sparks emergency in San Diego after four inches of rain in six hours

The National Weather Service said it was the wettest January day since records began in 1850

Flash flooding has sparked an emergency declaration in San Diego after four inches of rain fell in six hours on Monday.

San Diego mayor Todd Gloria declared a state of emergency after homes were inundated and cars were overturned as torrential rain swept through southern California over a roughly six-hour period on Monday.

Flood waters swept away vehicles and caused cars to pile on top of each other, while several feet of water inundated the Mountain View, Shelltown and Southcrest neighbourhoods, as well as multiple highways.

Meanwhile, three inches of rain fell in National City, while San Diego International Airport was hit with two inches of rain – the fifth-highest single-day total for any time of year since the National Weather Service began tracking rainfall totals in 1850, the San Diego Union-Tribune reported.

The San Diego Fire Department performed over 20 emergency rescue operations along the San Diego and Tijuana rivers, with at least eight migrants rescued after they were endangered by the floodwaters of the Tijuana River Valley on the US side, authorities said.

Hundreds of residents in Southcrest also had to be rescued by firefighters as standing water quickly surrounded their apartment complex, according to authorities. No injuries were reported.

A car sits along a flooded road during the rainstorm in San Diego (AP)

Mayor Gloria said a high school in San Diego was being used as a temporary shelter after about 100 homes were in some way affected by the flooding.

Sean Mahoney, regional CEO for the American Red Cross Southern California Region, added that the shelter would be able to house 375 people, providing hot meals and mental health support.

A woman walks by cars damaged by floods during a rainstorm in San Diego on Monday (AP)

Two homeless centres have also been relocated.

Further up north, the Los Angeles County Office of Emergency Management issued an evacuation warning near Topanga Canyon effective through Tuesday morning due to possible mud or debris flow.

Mayor Gloria has urged residents to stay off the roads amid the severe weather, which has also caused schools in La Mesa and Spring Valley to close.

“I strongly urge residents to please avoid any flooded areas and any unnecessary travel,” he said in a statement.

A woman removes debris from floods on Monday (AP)

Mayor Gloria added that while flooding was “predicted”, the short amount of time that the rain fell in was a “surprise.”

“This weather event was predicted, in terms of rain, but the amount of rain in the short amount of time was a bit of a surprise to, I think, everybody,” he said at a news conference on Tuesday.

Residents were also left in shock by the damage caused to the city in such a short space of time. Eddie Ochoa told the Associated Press he and his sister went out for breakfast on Monday morning and returned to find their entire block was flooded and his sister’s parked car had been washed away.

“All that happened within an hour,” Mr Ochoa said. He added that they later found his sister’s car about three miles down the street.

“It’s never been that bad, ever. It’s crazy,” he said.

Snowfall is also expected across large parts of California on Tuesday. An avalanche warning is in place for the backcountry in the mountains around the Lake Tahoe area, with more than a foot of snow expected in the region, according to the Sierra Avalanche Center in Truckee.

Monday’s storm came after an Arctic blast hit much of the US last week, bringing snow, flooding and freezing rain.

Cars swept down swamped roads as flooding wreaks havoc across San Diego (Accuweather)

Dozens of people are believed to have died from hyperthermia or road deaths caused by the treacherous conditions.

At a news conference, Mayor Gloria said he had just returned from a conference of US mayors in Washington, where attendees agreed that extreme weather, fueled by the climate crisis, was the new normal.

“It doesn’t matter what mayor from what part of the country, what you see is people having experiences exactly like this one,” he said.

“‘We’re used to snow, but not this much snow,’ or, ‘we’re used to rain but not this much rain.’ These unusual weather patterns that are really beyond people’s typical experience... it’s exactly what all of us are describing and why so many of us are so active on the issue of climate change.”

Additional reporting by the Associated Press