Peer into a backyard in Columbia Heights and a quartet plays. Walk down the waterfront on the Wharf and a masked instructor stretches into downward-facing dog. Dine on 17th Street NW and massage chairs sprawl across turf grass.

This was summer in the District — disease and desolation punctured by pockets of joyful commerce, spread across sidewalks, street corners and public parks.

Over the past few months, warm weather and entrepreneurial spirit have transformed many of D.C.’s public spaces into pandemic-sanctioned gathering spots. More than 550 restaurants have spread onto bike paths and parking lanes forming “Streateries” and “parklets”; and dozens of retailers and boutique fitness studios have moved their services outdoors in an effort to keep the businesses alive.

Before winter bears down, small-business owners and customers alike are determined to take advantage of the final temperate days as vital sources of revenue and relief. But looming over the city is a pervasive fear of winter, which threatens to clear the streets and send residents, wary of the health risks of socializing indoors, back to the confines of their homes. In an attempt to preserve D.C.’s outdoor economic activity, D.C. Mayor Muriel E. Bowser announced a new $4 million program Sunday to encourage businesses to stay open outdoors.

The Streatery Winter Ready Grant program will provide $6,000 grants to businesses that offer outdoor dining in the District, affording unrestricted funding to spend on promotional activity or equipment like heaters and tents. City permit regulations allow for tents as long as they have no more than one side flap. Applications opened Monday.

“The cold weather is obviously a challenge, but I think the same entrepreneurial spirit that got us through the summer will also help us get through the cold months,” said John Falcicchio, interim deputy mayor for planning and economic development. “I am just hopeful that this grant program will give restaurateurs the opportunity to look ahead toward the winter.”

In addition to the new relief drawn from Cares Act funding, the city announced Sunday it would delay insurance requirements that financially strain businesses operating as sidewalk cafes, streateries and parklets from January 2021 to January 2022. The city will also streamline approval of Streateries.

“The Streatery Winter Ready Grant program will keep our outdoor spaces open and more employees at work,” Bowser said in a statement.

Over the summer, experts say Washington area residents showed far more willingness to participate in outdoor activities than indoor ones — a trend aligned with a growing consensus among scientists that the novel coronavirus is less likely to spread in open air environments.

Michael Philips, music director at WOWD Takoma Radio, decided to harness enthusiasm around outdoor activities to revive live music in D.C. In August, he launched YardWork Concerts, a grass-roots organization that connects bands with homeowners interested in hosting small concerts in their backyards. Over the past few weeks, he employed six bands for 23 concerts.

“I am shaking because I am so excited to be hearing live music again,” said Joel Croft, 33, who on the first Saturday in September turned his Columbia Heights backyard into an intimate music venue, complete with string lights and five of his masked friends and neighbors.

Todd Marcus, a bass clarinetist, stood on a makeshift stage before him.

“We are grateful for those who have gotten creative about how to present our music,” he told the small audience, stressing that he and his bandmates had collectively lost more than $10,000 in income as a result of the pandemic.

The band started to play and music soared, drawing neighbors to their porches and stopping joggers around the corner.

Local restaurant owners have similarly turned city streets into colorful festivals, capitalizing on growing eagerness to dine alfresco. But the loss of income from indoor tables remains a struggle, they say, as they try to adjust to outdoor or takeout options to keep a revenue stream.

Bowser launched a Streateries program in late May, which expanded outdoor dining into parking and street lanes. On Sunday, she announced that the city would extend the permits for outdoor dining, originally set to expire in October, into the winter.

“I appreciate the efforts across District agencies to allow us to offer the Streatery Winter Ready Grand Program and additional relief options,” Shawn Townsend, director of the Mayor’s Office of Nightlife and Culture, said in a statement. That office partnered with the office of the deputy mayor for planning and economic development to develop the new program.

Other jurisdictions have also worked to help businesses find outdoor options. Donna Anderson, who owns barbecue house Sweet Fire Donna’s in Alexandria, had only two outdoor tables when the pandemic took hold in March. But with help from the city of Alexandria and the Carlisle District Council, she has since constructed a wood-floored patio that safely fits 10.

“It looks pretty sexy out there now,” she said, describing overhead plants that hang over the patio. “And I can’t tell you how much it has helped our sales.”

Like many local restaurateurs, Anderson said she has attracted new customers by bolstering her outdoor presence. Sales at Sweet Fire Donna’s have increased by 20 percent since the patio opened for business.

According to Kathy Hollinger, president of the Restaurant Association of Washington, 69 percent of local restaurant owners said in a recent survey that outdoor dining is “very important” to their business. But with summer ending and winter looming, the increased reliance on outdoor service is appearing less like a saving grace and more like an Achilles’ heel.

Debby Harper has sustained her D.C. nail salon by creating outdoor service stations of turf grass, plastic flowers and three massive massage chairs on wheels. She shudders thinking of snow falling and returning indoors, where almost no clients have felt comfortable booking an appointment.

“I am optimistic about fall, but it’s pretty scary to think about winter,” Harper said. “And we can’t push back the cold. It’s coming.”

Bracing for cold months, some local establishments have decided to shutter for the foreseeable future.

In a Tuesday announcement that shook longtime D.C. locals, hospitality giants Eric and Ian Hilton said they will close seven well-known bars and restaurants in and around Shaw — including Players Club and Brixton.

“The prospects of losing that lifeline of outdoor seating made it clear to us that it would be a real uphill battle in the cold months,” Ian Hilton said. “There comes a temperature threshold that people just can’t deal with.”

Hilton said that his outdoor venues were busy “in appearance,” but behind the scenes they were hemorrhaging money, unable to make up for the loss of indoor patrons.

Cathal Armstrong, chef and owner of Kaliwa restaurant in the Wharf, said the Hilton brothers’ announcement is just the tip of the iceberg.

“When the patio and outdoor seating closes, a lot of restaurants will have no choice but to close,” he said. “I know I don’t want to close, but at the end of the day, it’s an equation. It is money going in versus money going out.”

Falcicchio and his partners in the city government said the grant program and delayed insurance requirements should act as stopgap measures until the federal government can pour more substantial support into the local business community.

Until then, they encourage locals to take advantage of the fresh-air activity as respite from the daily slog of quarantined life, like the group enjoying live music from a D.C. yard.

“We will do this until the weather gets cold,” Philips said, listening to the Todd Marcus Jazz Quartet perform that Saturday. “So let’s just enjoy it.”