Bernal

Instead, the business owners and residents in these neighborhoods — which includes areas in the Mission, West Portal and around Lower Alemany — will largely have to rely on old-school tactics to protect their properties, like flood barriers and sandbags.

San Francisco is already struggling to clean up after the New Year’s Eve deluge as it tries to prepare for the next storm. The city is particularly prone to flooding because, unlike every other coastal California city that has a separate sewer system, San Francisco uses the same set of pipes and can be easily overwhelmed by heavy rains, especially in low-lying areas.

In anticipation of the upcoming storm, city officials have already activated an Emergency Operations Center. San Francisco Public Works distributed more than 8,500 sandbags by early afternoon Tuesday but was running low and had to limit the number to five per household.

Officials also began propping up flood barriers around 17th and Folsom streets, one of the most vulnerable places in the city for extreme flooding.

But despite round-the-clock preparations, Mayor London Breed said at a news conference Tuesday that the situation is not completely within the city’s control. San Francisco has seen rain of this magnitude only a few other times in its history, she said, pointing to climate change as one driver of extreme weather events.

Still, neighborhood advocates said the city has dragged its feet in making critical upgrades to its drainage system.

“This has been going on for years,” said David Hooper, a Mission Terrace resident who is with Solutions Not Sandbags, a local group advocating for better sewers. Hooper pointed to repeat flooding and sewer backups in the Mission, his neighborhood, and Alemany and Folsom.

“The immediate storm will be what it will be,” he said. “Because the city has avoided addressing this issue for so long, the storm will happen…. And so people will end up suffering, as they did Saturday, and a year ago, and 2019, and in 2014. The situation has to change.”

As part of the San Francisco Public Utility Commission’s 10-year capital plan, $632 million has been allocated through 2032 to improve stormwater management in problem areas around the city. Those projects are targeted for 15th Avenue and Wawona Street in the West Portal neighborhood, 17th and Folsom streets in the Mission District, and the Lower Alemany area in Bernal Heights.

More Information

How to get help

San Francisco officials said one way for residents to help the city’s storm response go smoothly is to call 911 only in the case of a life-threatening emergency. Residents experiencing flooding issues should call 311 instead.

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The projects were part of a deal with the San Francisco Bay Regional Water Quality Control Board in 2021.

The agreement required San Francisco to expand the capacity of its sewer system in those three areas. When sewage and stormwater flood sidewalks and into garages and houses, they “contain pathogens and other pollutants that pose human health risks and threaten groundwater quality,” according to the water board.

All of the projects, which must be completed no later than 2028, are still years away from completion, meaning the targeted neighborhoods are still vulnerable to this week’s rainfall.

“We are trying to figure out what to do for some of our constituents,” Santiago Lerma, an aide for Mission District Supervisor Hillary Ronen, said Tuesday morning.

The improvement project for that area is currently in the design phase and expected to be completed by 2027 and will cost an estimated $298 million. In the meantime, Lerma said, residents and business owners largely have to rely on Band-Aids — like sandbags and flood barriers — to protect themselves from major rainstorms.

Weather forecasts this past weekend severely underestimated how severe the storm would be, officials said Tuesday. As a result, Lerma said, officials did not bring out the flood barriers that would have mitigated some of the damages around 17th and Folsom.

“But a storm half that size would have still flooded 17th and Folsom,” he said. “It’s the most notorious flooding site in the city. … “There could have been better preparation. We knew that the storms were coming.”

At a news conference Tuesday, San Francisco Public Utilities Commission General Manager Dennis Herrera said the city is prioritizing the low-lying neighborhoods and clearing storm drains in the area. Out of an abundance of caution, he said, the city is also deploying the floor barriers in the Mission ahead of Wednesday’s storm.

Along with the short-term mitigation efforts and the long-term infrastructure projects, Herrera said the city also has hundreds of smaller projects around the city — like creating rain gardens — that are “incorporating green infrastructure and stormwater resiliency.”

“The PUC is investing in great infrastructure projects in recognition that we do have a changing normal,” he said. “We have to continue to look at how we can attack it in a very, very comprehensive way.”

Near 15th Avenue and Wawona Street on Tuesday afternoon, Ray Moreno was standing in his garage, fixing a small pump in preparation for the coming storm. That area’s stormwater management project is under way and is expected to be completed by late 2024.

“The sewers held” during the most recent New Year’s Eve deluge, he said. Moreno said he had to use the pump to clear his backyard of water during that most recent storm, but a number of upgrades he’s made to his home in recent years have helped him keep ahead of any flooding in this low-lying part of the neighborhood.

Those include installing a device in his concrete garage floor that prevents water from coming back up from city pipes, installing extra runoff grates in the driveway, and grading it so it slopes to the street.

Moreno said he was also confident that the sewer upgrades the city recently made in the area would be able to handle the storm expected on Wednesday. Drains have backed up in the past and wrecked the lower levels of nearby residents’ homes.

No city crews were in sight shortly before noon on Tuesday in the area. One pickup truck trundled by, its bed packed with sandbags, headed for the nearby Arden Wood retirement community.

Moreno said that since moving into the house in 1985, he’s dealt with weather-related flooding, sometimes causing his shower to overflow with stormwater.

Moreno seemed calm despite the impending storm. “It’s just a waiting game now,” he said.

Other residents and businesses were not as lucky.

At Rainbow Grocery Cooperative at Folsom near 14th Street, the weekend rains turned the loading dock “into a swimming pool,” spokesperson David Higgins said.

Some of the store’s workers lost their cars during Saturday’s flooding, he added.

“The whole area has been damaged extensively, but it wasn’t as bad for us as some of our neighbors,” he said.

“We’re open today,” he said. “So that’s something.”

Trisha Thadani (she/her), Chase DiFeliciantonio and St. John Barned-Smith are San Francisco Chronicle staff writers. Email: [email protected] Twitter: @TrishaThadani

When will today’s rains let up?

For residents waking up after 9 a.m. Friday morning, the good news is that the bulk of moderate rain showers will already be halfway to the Sierra Nevada.

That’s because the cold front out ahead of the low-pressure system is forecast to roll into the Bay Area between 2 and 6 a.m. Friday’scold front will carry the majority of the moderate rain showers slated for San Francisco, Oakland, San Rafael and the rest of San Francisco Bay.

Unfortunately, that means morning commuters coming into San Francisco from the Santa Clara Valley, East Bay hills, Peninsula and North Bay valleys will be contending with slippery roadways from these moderate rain showers right around the peak of the morning rush hour. The same goes for muni and BART riders who may come across delays if some of these showers briefly stall over San Francisco and Oakland.

Thankfully, weather models — including the North American weather model that often forecasts higher rainfalls in its simulations for the Bay Area than what actually plays out – are leaning toward a scenario where the cold front quickly exits the Bay Area after 9 a.m.

The rest of the morning looks to be mostly a shower-fest for the San Francisco Peninsula, East Bay hills, Marin County and Sonoma County coastline and the 101 corridor east from Morgan Hill to Gilroy. Look for spotty showers across most of the Bay Area through 1 p.m. before they all slowly fizzle away Friday afternoon.

All the extra clouds overhead tonight will also help to trap heat from earlier in the day, keeping nighttime lows on the warmer side. So, expect a comfortable, cloudy night across most of the Bay Area with temperatures in the upper 40s and lower 50s.

Is there still another chance for rain this weekend?

After a brief break from the rain, a second low-pressure system will roll into Northern California by noon on Saturday. This system will have a bit more of a kick to it, churning up 25 to 35 mph gusts across most of San Francisco and the wider Bay Area on Saturday afternoon.

These steadfast winds will be accompanied by light to moderate rain showers through Sunday evening, with the heaviest showers slated for late Saturday night into early Sunday morning.

Will there be an elevated risk for flooding like last month?

These rain showers are forecast to raise rainfall totals between an inch to an inch and a half of rain across most bayside cities.Higher peaks in the hillsides and mountains will get closer to 2 inches, while the mountains in the North Bay and in San Mateo and Santa Cruz counties could get as much as 3 inches of rain before all is said and done.

Thankfully, this rainfall will be scattered over the course of three days, rather than the three hours seen at the height of the New Year’s Eve storm in San Francisco. But, given that the soils are still saturated from January’s deluge, it’s important to practice safe driving on slippery roadways and to stay alert for landslides in more rural areas.

Weekend breakdown

• San Francisco: A low-pressure system will set up shop over San Francisco Bay Friday morning and usher rounds of moderate rain to Sutro Tower, Bernal Heights, Mount Davidson and a few other hillsides by West Portal. Brief downpours will be possible on the west side through 9 a.m. as showers darken the skies over the Sunset and Richmond districts. Some of these moderate showers will eventually stream east of Sutro Tower and into the Castro, downtown and SoMa between 8 a.m. and 11 a.m. before trailing into San Francisco Bay. Brief showers will then be possible through 3 p.m. across the city before they eventually fizzle away. Look for daytime highs on Friday that will peak in the lower 60s between Muni’s lines from West Portal to the Embarcadero, while commuters heading down to Glen Park and Sunnydale this afternoon will be in for highs in the upper 50s.

The dry weather will hang around through noon on Sunday before the next round of rain showers streams into the city. Have a raincoat or umbrella handy for Saturday and Sunday because these showers will last all the way through Sunday afternoon. Look for daytime highs in the lower 60s on Saturday before winds and showers pick up in the evening. Some of the windiest spots will develop overnight and into Sunday morning along the water and bays, reaching 35 mph in Ocean Beach, the Presidio, Embarcadero and Hunter’s Point. By Sunday afternoon, these showers and winds will drop off and make way for a chilly, cloudy day with highs in the mid-50s.

• Pacific Coast and Peninsula: Rounds of showers will begin streaming into the coastline today and through the evening as highs reach the upper 50s region-wide. Light to moderate rainbands will impact most of Highway 1 between Half Moon Bay and Pacifica as winds pick up to 30 mph this afternoon. Brief, heavy bands of rain will be possible in the San Bruno Gap but expect most showers to be light and moderate through 4 p.m. this afternoon. BART riders at San Francisco International Airport and Daly City will likely come across a wet morning and evening commute home before showers finally leave the Peninsula this evening.

The dry weather tonight and into Saturday morning will help clear out slippery conditions on Highway 92 between Half Moon Bay and San Mateo, but expect those conditions to come back by Saturday afternoon as 25 to 30 mph bring showers back to the Peninsula. Look for daytime highs in the lower 60s on Friday along Highway 1 while upper 50s will be found in Daly City, South San Francisco and Millbrae.

All the clouds from Saturday afternoon’s showers will keep nighttime lows in the lower 50s on the coast, while cities along the 101 corridor south of Millbrae are likely to fall to the upper 40s Saturday night and into Sunday morning thanks to breaks in the clouds. Expect bursts of moderate rain to spread to the San Bruno Gap and most of Highway 1 from 11 p.m. on Saturday through Sunday morning.

Showers will fizzle away across the Peninsula by Sunday afternoon, leaving behind a trail of cool air that will keep Sunday’s highs in the mid-50s.

• North Bay: Residents in the Petaluma, Santa Rosa and Napa valleys — along with some of the summits in the Marin headlands — will be waking up to the sound of rain this morning. These showers will peak right around 6 a.m. before slowly breaking apart through Friday afternoon. Watch for slippery roadways if you plan on traveling along Highways 101, 29 and 17 this morning. Look for clearer skies and highs in the upper 50s by 3 p.m. as conditions improve.

This break in the weekend rain-fest will continue until noon on Saturday, when skies will darken as the next round of rain showers sweep onto the Sonoma County and Marin County coastline. Light to moderate showers will spread east on Saturday evening, keeping temperatures in the mid-50s as they once again bring slippery conditions to roadways across the region.Patches of Napa and Sonoma counties, including Healdsburg and Guerneville, will experience moderate to heavy rainfall tonight and into early Sunday morning, but these rains will quickly weaken by dawn and turn to light showers over the course of the day on Sunday.

Expect Saturday afternoon and Sunday afternoon to be socked in with light showers all across the North Bay, including San Pablo Bay, the delta, the banana belt along 101 from Novato to San Rafael and cities along Highways 37, 80 and 780 in Solano County. Most of these showers will clear by 1 p.m. on Sunday and make way for a cloudy evening with temperatures in the low to mid-50s.Residents along the Marin Headlands and Sonoma coast will be the last to clear out from the rain on Sunday, with light showers persisting through 5 p.m.

• East Bay: The pitter-patter sounds of rain will make their way into all corners of the East Bay Friday morning, with Alameda Island, the Oakland and Berkeley hills and valleys near the Caldecott Tunnel seeing some of the heaviest showers. Most East Bay residents along the I-80/I-880 corridors will get a taste of moderate rain showers before they taper off around 1 p.m.

Some of these rain showers will survive into Friday afternoon, keeping most of the I-680 corridor rain-soaked until 4 p.m. Daytime highs across Alameda and Contra Costa counties will recover from the cloudy and rainy morning and rise to the upper 50s to lower 60s. By Saturday afternoon, temperatures will reach the upper 50s before skies become overcast again. Another round of showers will break through the Oakland and Berkeley hills. Look for more widespread showers along San Francisco Bay by Saturday evening and eventually in interior cities like Concord, Walnut Creek and the San Ramon and Livermore by Saturday night.

Low-lying areas in Oakland, Fremont, Hayward and Richmond will see their lion’s share of ponding and minor urban flooding, but these weather hazards will subside by Sunday morning as showers weaken. There is a slight risk of damage to loose objects from these showers as northwest winds — reaching gusts to 30 mph —spread into the region during the overnight hours. These winds will largely drop off by Sunday afternoon as rain fizzles away and makes way for a cloudy, chilly Sunday with highs in the mid-50s.

• South Bay and Santa Cruz: A rainy start to Friday is on tap for the Santa Clara Valley and the Santa Cruz Mountains. Light sprinkles from a low-pressure system will soak most of the South Bay and Central Coast today and then again on Saturday afternoon through Sunday morning. Rainfall totals in San Jose, Milpitas and Sunnyvale, and coastal areas of Santa Cruz, Aptos and Capitola are expected to reach an inch and a half. Residents in the Santa Cruz Mountains will likely see higher totals— up to 3 inches of rain — before all is said and done.

Thankfully, these rainfall totals will be scattered out over the course of 3 days, keeping flood risks low. Residents along the highway 101 and 17 corridors will see slippery conditions on Friday morning and then again Saturday night into Sunday morning as the two rounds of rain stream over the region.

Look for daytime highs on Friday and Saturday in the upper 50s to lower 60s. Some of the warmest spots will be in the wind-sheltered Santa Clara Valley where San Jose, Los Gatos and Morgan Hill will likely climb to the mid-60s once again. But it all goes downhill by Sunday as cold air from this weekend’s low-pressure system drops temperatures by 7 to 10 degrees in the valley, keeping daytime highs in the mid-50s.

Gerry Díaz (he/they) is a San Francisco Chronicle newsroom meteorologist. Email: [email protected] Twitter @geravitywave

When will today’s rains let up?

For residents waking up after 9 a.m. Friday morning, the good news is that the bulk of moderate rain showers will already be halfway to the Sierra Nevada.

That’s because the cold front out ahead of the low-pressure system is forecast to roll into the Bay Area between 2 and 6 a.m. Friday’s cold front will carry the majority of the moderate rain showers slated for San Francisco, Oakland, San Rafael and the rest of San Francisco Bay.

Unfortunately, that means morning commuters coming into San Francisco from the Santa Clara Valley, East Bay hills, Peninsula and North Bay valleys will be contending with slippery roadways from these moderate rain showers right around the peak of the morning rush hour. The same goes for Muni and BART riders who may come across delays if some of these showers briefly stall over San Francisco and Oakland.

Thankfully, weather models — including the North American weather model that often forecasts higher rainfall in its simulations for the Bay Area than what actually plays out — are leaning toward a scenario where the cold front quickly exits the Bay Area after 9 a.m.

The rest of the morning looks to be mostly a shower-fest for the Peninsula, East Bay hills, Marin County and Sonoma County coastline, and the 101 corridor east from Morgan Hill to Gilroy. Look for spotty showers across most of the Bay Area through 1 p.m. before they all slowly fizzle away Friday afternoon.

All the extra clouds overhead Friday night will also help to trap heat from earlier in the day, keeping nighttime lows on the warmer side. So expect a comfortable, cloudy night across most of the Bay Area with temperatures in the upper 40s and lower 50s.

Is there still another chance for rain this weekend?

After a brief break from the rain, a second low-pressure system will roll into Northern California by noon on Saturday. This system will have a bit more of a kick to it, churning up 25- to 35-mph gusts across most of San Francisco and the wider Bay Area on Saturday afternoon.

These steadfast winds will be accompanied by light to moderate rain showers through Sunday evening, with the heaviest showers slated for late Saturday night into early Sunday morning.

Will there be an elevated risk for flooding like last month?

These rain showers are forecast to raise rainfall totals between an inch and an inch and a half across most bayside cities. Higher peaks in the hillsides and mountains will get closer to 2 inches, while the mountains in the North Bay and in San Mateo and Santa Cruz counties could get as much as 3 inches of rain before all is said and done.

Thankfully, this rainfall will be scattered over the course of three days, rather than the three hours seen at the height of the New Year’s Eve storm in San Francisco. But, given that the soils are still saturated from January’s deluge, it’s important to practice safe driving on slippery roadways and to stay alert for landslides in more rural areas.

Weekend breakdown

• San Francisco: A low-pressure system will set up shop over San Francisco Bay on Friday morning and usher rounds of moderate rain to Sutro Tower, Bernal Heights, Mount Davidson and a few other hillsides by West Portal. Brief downpours will be possible on the west side through 9 a.m. as showers darken the skies over the Sunset and Richmond districts. Some of these moderate showers will eventually stream east of Sutro Tower and into the Castro, downtown and SoMa between 8 a.m. and 11 a.m. before trailing into San Francisco Bay. Brief showers will then be possible through 3 p.m. across the city before they eventually fizzle away. Look for daytime highs on Friday that will peak in the lower 60s between Muni’s lines from West Portal to the Embarcadero, while commuters heading down to Glen Park and Sunnydale this afternoon will be in for highs in the upper 50s.

The dry weather will hang around through noon on Sunday before the next round of rain showers streams into the city. Have a raincoat or umbrella handy for Saturday and Sunday because these showers will last all the way through Sunday afternoon. Look for daytime highs in the lower 60s on Saturday before winds and showers pick up in the evening. Some of the windiest spots will develop overnight and into Sunday morning along the water and bays, reaching 35 mph at Ocean Beach, the Presidio, the Embarcadero and Hunters Point. By Sunday afternoon, these showers and winds will drop off and make way for a chilly, cloudy day with highs in the mid-50s.

• Pacific Coast and Peninsula: Rounds of showers will begin streaming into the coastline Friday and through the evening as highs reach the upper 50s region-wide. Light to moderate rainbands will impact most of Highway 1 between Half Moon Bay and Pacifica as winds pick up to 30 mph Friday afternoon. Brief, heavy bands of rain will be possible in the San Bruno Gap, but expect most showers to be light and moderate through 4 p.m. Friday afternoon. BART riders at San Francisco International Airport and Daly City will likely come across a wet morning and evening commute home before showers finally leave the Peninsula on Friday evening.

The dry weather Friday night and into Saturday morning will help clear out slippery conditions on Highway 92 between Half Moon Bay and San Mateo, but expect those conditions to come back by Saturday afternoon as 25- to 30-mph winds bring showers back to the Peninsula. Look for daytime highs in the lower 60s on Friday along Highway 1, while upper 50s will be found in Daly City, South San Francisco and Millbrae.

All the clouds from Saturday afternoon’s showers will keep nighttime lows in the lower 50s on the coast, while cities along the 101 corridor south of Millbrae are likely to fall to the upper 40s Saturday night and into Sunday morning thanks to breaks in the clouds. Expect bursts of moderate rain to spread to the San Bruno Gap and most of Highway 1 from 11 p.m. on Saturday through Sunday morning.

Showers will fizzle away across the Peninsula by Sunday afternoon, leaving behind a trail of cool air that will keep Sunday’s highs in the mid-50s.

• North Bay: Residents in the Petaluma, Santa Rosa and Napa valleys — along with some of the summits in the Marin headlands — will be waking up to the sound of rain Friday morning. These showers will peak right around 6 a.m. before slowly breaking apart through Friday afternoon. Watch for slippery roadways if you plan on traveling along Highways 101, 29 and 17 Friday morning. Look for clearer skies and highs in the upper 50s by 3 p.m. as conditions improve.

This break in the weekend rain-fest will continue until noon on Saturday, when skies will darken as the next round of rain showers sweeps onto the Sonoma County and Marin County coastline. Light to moderate showers will spread east on Saturday evening, keeping temperatures in the mid-50s as they once again bring slippery conditions to roadways across the region. Patches of Napa and Sonoma counties, including Healdsburg and Guerneville, will experience moderate to heavy rainfall Friday night and into early Sunday morning, but these rains will quickly weaken by dawn and turn to light showers over the course of the day on Sunday.

Expect Saturday afternoon and Sunday afternoon to be socked in with light showers all across the North Bay, including San Pablo Bay, the delta, the banana belt along 101 from Novato to San Rafael and cities along Highway 37, and Interstate 80 and I-780 in Solano County. Most of these showers will clear by 1 p.m. on Sunday and make way for a cloudy evening with temperatures in the low to mid-50s. Residents along the Marin Headlands and Sonoma coast will be the last to clear out from the rain on Sunday, with light showers persisting through 5 p.m.

• East Bay: The pitter-patter sounds of rain will make their way into all corners of the East Bay on Friday morning, with Alameda Island, the Oakland and Berkeley hills, and valleys near the Caldecott Tunnel seeing some of the heaviest showers. Most East Bay residents along the I-80/I-880 corridors will get a taste of moderate rain showers before they taper off around 1 p.m.

Some of these rain showers will survive into Friday afternoon, keeping most of the I-680 corridor rain-soaked until 4 p.m. Daytime highs across Alameda and Contra Costa counties will recover from the cloudy and rainy morning and rise to the upper 50s to lower 60s. By Saturday afternoon, temperatures will reach the upper 50s before skies become overcast again. Another round of showers will break through the Oakland and Berkeley hills. Look for more widespread showers along San Francisco Bay by Saturday evening and eventually in interior cities like Concord, Walnut Creek, and the San Ramon and Livermore valleys by Saturday night.

Low-lying areas in Oakland, Fremont, Hayward and Richmond will see their lion’s share of ponding and minor urban flooding, but these weather hazards will subside by Sunday morning as showers weaken. There is a slight risk of damage to loose objects from these showers as northwest winds — reaching gusts to 30 mph —spread into the region during the overnight hours. These winds will largely drop off by Sunday afternoon as rain fizzles away and makes way for a cloudy, chilly Sunday with highs in the mid-50s.

• South Bay and Santa Cruz: A rainy start to Friday is on tap for the Santa Clara Valley and the Santa Cruz Mountains. Light sprinkles from a low-pressure system will soak most of the South Bay and Central Coast on Friday and then again on Saturday afternoon through Sunday morning. Rainfall totals in San Jose, Milpitas and Sunnyvale, and coastal areas of Santa Cruz, Aptos and Capitola, are expected to reach an inch and a half. Residents in the Santa Cruz Mountains will likely see higher totals— up to 3 inches of rain — before all is said and done.

Thankfully, these rainfall totals will be scattered out over the course of three days, keeping flood risks low. Residents along the highways 101 and 17 corridors will see slippery conditions on Friday morning and then again Saturday night into Sunday morning as the two rounds of rain stream over the region.

Look for daytime highs on Friday and Saturday in the upper 50s to lower 60s. Some of the warmest spots will be in the wind-sheltered Santa Clara Valley where San Jose, Los Gatos and Morgan Hill will likely climb to the mid-60s once again. But it all goes downhill by Sunday as cold air from this weekend’s low-pressure system drops temperatures by 7 to 10 degrees in the valley, keeping daytime highs in the mid-50s.

Gerry Díaz (he/they) is a San Francisco Chronicle newsroom meteorologist. Email: [email protected] Twitter @geravitywave