On San Antonio's South Side, a group of about 20 parishioners hurried one by one from the parking lot into a tiny church that can't hold more than several dozen. 

Their frilly dresses quickly soaked with rain, their shiny shoes were also instantly ruined in deepening puddles and the flowers some were carrying whipped out of their hands and disappeared. 

But Jessica Garcia had a good reason to brave the wind and the rain.

She was holding her son Jacob in her arms.

"No matter what the weather, we know that God's going to help him get baptized," Garcia said. 

Fallen Tree

Winds and downed trees aren't the biggest problem for San Antonio: it's the rain. (Kim Brunhuber/CBC)

She couldn't see Harvey yet, but could feel the storm building. Wind vanes were churning like propellers. The rain saturated already-soaked ground. Roofs were covered with tarps that look ready to rip off as though they were Band-Aids. 

San Antonio lies in what's called a flash flood alley, with those living near this old mission seemingly directly in its path. 

Mission area house

Many houses in San Antonio, like this one in the Mission Espada area, are built on low-lying ground. (Kim Brunhuber/CBC)

Harvey unloaded extraordinary amounts of rain Saturday after it crashed into homes and businesses along the coastline in a blow that killed at least two people and injured more than a dozen others.

Throughout the region between Corpus Christi and Houston, authorities did not know the full scope of damage because weather conditions prevented emergency crews from getting into the hardest-hit places. The storm was expected to linger for days and unload more than 100 centimetres of rain on cities, including dangerously flood-prone Houston, the fourth-largest in the U.S.

On Sunday, flooding in some parts of the county that includes the city of Houston was so bad that residents were being urged to seek refuge on their roofs.

Harris County Flood Control District official Jeff Lindner said people inundated by rising waters shouldn't crawl into attics of their homes but should get on top of them. He says rainfall of more than 10 centimetres per hour has sent water higher than in recent Houston floods side and were exceeding levels seen in Tropical Storm Allison in June 2001.

Back in San Antonio before the storm unleashed its greatest fury, Marco Longoria recalled to CBC that the community surrounding Mission Espada, which is built on flat, low-lying ground, and has the San Antonio River as its neighbour, was devastated by flooding four years ago.

"It's kind of dangerous sometimes when it rains a lot," Longoria said. 

San Antonio River-2

One major flooding risk: the San Antonio River, which overflowed during storms in 1998 and 2002. (Kim Brunhuber/CBC)

That's why Andres Gallegos, the pastor at Mission Espada, said Saturday would mark the last service until further notice. He had to turn to more secular matters in order to ensure that this 200-year-old church is still standing next week.

"We're going to talk about this," Gallegos said. "I think we need to make some decisions."

Stocking up

There was a run on staples at many grocery stores, as San Antonio residents prepared for possible flooding. (Kim Brunhuber/CBC)

The suburbs and outskirts were the only areas at risk of flooding.

The San Antonio River snakes through the downtown core; its famed River Walk boasts a network of walkways with shops and restaurants on either side.

With the prospect of flooding, some shops chose to close and spread tarps over their windows.

Several grocery stores had seen runs on staples. At one H-E-B grocery store near downtown, an elderly woman brushed past, muttering to herself about how she was probably too late because "everyone bought up the water."

Shuttered business

Many San Antonio businesses chose to close for the weekend. (Kim Brunhuber/CBC)

"We've created additional flood control infrastructure that has helped us cope," Mayor Ron Nirenberg told CBC News. "We've invested hundreds of millions of dollars, if not billions of dollars over the years, particularly in the last 20 years to cope with major flooding events," 

And that gave some residents living in flood-prone areas a sense of calm despite the storm.  

Riverwalk

Downtown San Antonio is full of canals, but experts didn't expect them to flood. (Kim Brunhuber/CBC)

"We have a pretty robust flood system in San Antonio," Eric Warner said, smiling. "I think it'll do its job."

But those attending little Jacob's baptism at Mission Espada chose to put their faith elsewhere. They felt the river was too powerful — their houses too close.

Mission Espada-2

The Garcias said they were relying on their faith to get them through the aftermath of Harvey. (Kim Brunhuber/CBC)

"I know God will help us get through this day, through this hurricane," Garcia said, taking her seat in the pew to pray.